iShares S&P GSCI Commodity-Indexed Trust - Quarter Report: 2011 September (Form 10-Q)

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

For the quarterly period ended September 30, 2011

For the transition period from              to             

Commission file numbers: 001-32947 (Registrant)

                                                     001-32948 (Co-Registrant)

iShares^® S&P GSCI™ Commodity-Indexed Trust

iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

(Rule 140 Co-Registrant)

(Exact name of Registrant as specified in its charter)

c/o BlackRock Asset Management International Inc.

400 Howard Street

San Francisco, California 94105

Attn: Product Management Team

iShares^® Product Research & Development

(Address of principal executive offices)

(415) 670-2000

(Registrant and Co-Registrant’s telephone number, including area code)

N/A

(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the Registrant and Co-Registrant (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant and Co-Registrant were required to file such reports), and (2) have been subject to such filing requirements for the past 90

days.    Yes  x    No  ¨

Indicate by check mark whether the Registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the Registrant and Co-Registrant are shell companies (as defined in Rule 12b-2 of the Exchange

Act).    Yes  ¨    No  x

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PART I – FINANCIAL INFORMATION

Item 1. Financial Statements

iShares^® S&P GSCI™ Commodity-Indexed Trust

Statements of Financial Condition

At September 30, 2011 (Unaudited) and December 31, 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Statements of Operations (Unaudited)

For the three and nine months ended September 30, 2011 and 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Statements of Changes in Shareholders’ Capital

For the nine months ended September 30, 2011 (Unaudited)

and the year ended December 31, 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Statements of Cash Flows (Unaudited)

For the nine months ended September 30, 2011 and 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Notes to Financial Statements (Unaudited)

September 30, 2011

1 - Organization

The iShares^® S&P GSCI™ Commodity-Indexed Trust (the “Trust”) was organized as a Delaware statutory trust on July 7, 2006 and commenced operations on July 10, 2006. Prior to May 9, 2007, the Trust was known as the iShares^® GSCI^® Commodity-Indexed Trust. BlackRock Asset Management International Inc. (“BAMII”) is the “Sponsor” of the Trust and “Manager” of the iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC (the “Investing Pool”). BlackRock Institutional Trust Company, N.A. is the “Trustee” of the Trust. The Trust is governed by the Amended and Restated Trust Agreement, dated as of September 12, 2007 (the “Trust Agreement”), among the Sponsor, the Trustee and Wilmington Trust Company (the “Delaware Trustee”). The Trust issues units of beneficial interest (“Shares”) representing fractional undivided beneficial interests in its net assets. Substantially all of the net assets of the Trust consist of its holdings of the limited liability company interests of a commodity pool, which are the only securities in which the Trust may invest. That commodity pool, iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC, holds long positions in futures contracts on the S&P GSCI™ Excess Return Index listed on the Chicago Mercantile Exchange called Commodity Excess Return Futures (“CERFs”) and posts margin in the form of cash or short-term or similar securities, referred to as “Short-Term Securities,” to collateralize its CERF positions. Margin has to be posted at the time the CERF position is established.

It is the objective of the Trust that the performance of the Shares will correspond generally to the performance of the S&P GSCI™ Total Return Index before payment of the Trust’s and the Investing Pool’s expenses.

The Trust and the Investing Pool are each commodity pools, as defined in the regulations of the Commodity Futures Trading Commission (the “CFTC”) and are operated by BAMII, a commodity pool operator registered with the CFTC. BAMII is an indirect subsidiary of BlackRock, Inc.

The Trustee has the absolute right to reject any creation order, including, without limitation, creation orders that the Trustee has determined would have adverse tax or other consequences to the Trust, its shareholders or the Investing Pool. The Trust disclosed through a filing on Form 8-K on August 21, 2009 that the Trustee expected to reject any creation orders for Shares of the Trust upon the Trust reaching Shares outstanding of approximately 55,900,000 in order to continue to manage the assets of the Trust and the Investing Pool consistent with their investment objective. The Trust received creation orders on August 24, 2009 that would have exceeded that number of Shares, and accordingly stopped accepting further creation orders temporarily. The Trust resumed accepting creation orders on April 27, 2010.

The accompanying unaudited financial statements were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions for Form 10-Q and the rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”). In the opinion of management, all material adjustments, consisting only of normal recurring adjustments, considered necessary for a fair statement of the interim period financial statements have been made. Interim period results are not necessarily indicative of results for a full-year period. These financial statements and the notes thereto should be read in conjunction with the Trust’s financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2010 as filed with the SEC on February 25, 2011.

The Trust is not an investment company registered under the Investment Company Act of 1940, as amended.

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

2 - Summary of Significant Accounting Policies

The following is a summary of significant accounting policies consistently followed by the Trust in the preparation of its financial statements in conformity with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates and these differences could be material.

The Trust’s investment in the Investing Pool is valued at an amount equal to the value of the Trust’s capital account in the Investing Pool, which is measured at fair value.

The financial statements of the Investing Pool should be read in conjunction with the Trust’s financial statements.

At September 30, 2011, the Trust owned 99.99% of the Investing Pool’s net assets. Because the Trust invests substantially all of its assets in the Investing Pool, the accounting policies of the Investing Pool, including the Investing Pool’s security valuation policies, will directly affect the recorded value of the Trust’s investment in the Investing Pool. The Trust also receives a daily allocation of its respective income, expenses and net realized and unrealized gains and losses in proportion to its investment in the Investing Pool.

The Trust is not an association taxable as a corporation for federal, state and local income tax purposes.

No provision for federal, state, and local income taxes has been made in the accompanying financial statements because the Trust is not subject to income taxes. Shareholders are individually responsible for their own tax payments on their proportionate share of gains, losses, credits, or deductions.

The net asset value of the Trust on any given day is obtained by subtracting the Trust’s accrued expenses and other liabilities on that day from the value of (1) the Trust’s equity investment in the Investing Pool and (2) any other assets of the Trust, as of 4:15 p.m. (New York time) that day. The Trustee determines the net asset value per Share (the “NAV”) by dividing the net asset value of the Trust on a given day by the number of Shares outstanding or deemed to be outstanding at 4:15 p.m. (New York time) that day. The NAV is calculated each day on which NYSE Arca, Inc. (“NYSE Arca”) is open for regular trading, as soon as practicable after 4:15 p.m. (New York time).

Interest and distributions received by the Investing Pool on the assets posted as margin may be used to acquire additional CERFs or, in the discretion of the Sponsor, distributed to Shareholders. The Trust is under no obligation to make periodic distributions to Shareholders.

In May 2011, the Financial Accounting Standards Board issued amended guidance to improve disclosure about fair value measurements which will require the following disclosures for fair value measurements categorized as Level 3: quantitative information about the unobservable inputs and assumptions used in the fair value measurement, a description of the valuation

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iShares^® S&P GSCI^™ Commodity-Indexed Trust

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

policies and procedures and a narrative description of the sensitivity of the fair value measurement to changes in unobservable inputs and the interrelationships between those unobservable inputs. In addition, the amounts and reasons for all transfers in and out of Level 1 and Level 2 will be required to be disclosed. The amended guidance is effective for financial statements for fiscal years beginning after December 15, 2011, and interim periods within those fiscal years. Management is evaluating the impact of this guidance on the Trust’s financial statements and disclosures.

3 - Offering of the Shares

Shares are issued and redeemed continuously in one or more blocks of 50,000 Shares in exchange for a combination of CERFs and cash (or, in the discretion of the Sponsor, Short-Term Securities in lieu of cash). The baskets of CERFs and cash (or, in the discretion of the Sponsor, Short-Term Securities in lieu of cash) are transferred to or from the Investing Pool in exchange for limited liability company interests in the Investing Pool. In addition, the Investing Pool is required to deposit cash margin with its futures commission merchant with a value equal to 100% of the value of each CERF position at the time it is established.

Individual investors cannot purchase or redeem Shares in direct transactions with the Trust. The Trust transacts only with registered broker-dealers that have entered into a contractual arrangement with the Trust and the Sponsor governing, among other matters, the creation and redemption of Shares (such authorized broker-dealers are the “Authorized Participants”). Authorized Participants may redeem their Shares (as well as Shares on behalf of other investors) at any time on any business day in one or more blocks of 50,000 Shares. Redemptions of Shares in exchange for baskets of CERFs and cash (or, in the discretion of the Sponsor, Short-Term Securities in lieu of cash) are treated as sales for financial statement purposes.

On April 27, 2010, the Trust resumed accepting creation orders. Creation of new Shares of the Trust had been suspended since August 24, 2009.

On September 30, 2011, the Trust had 41,650,000 Shares outstanding.

4 - Trust Expenses

The Trust is not expected to directly bear any ordinary recurring expenses. The Sponsor has agreed to pay the following administrative, operational and marketing expenses: (1) the fees of the Trustee, Delaware Trustee, Trust administrator and processing agent, (2) NYSE Arca listing fees, (3) printing and mailing costs, (4) audit fees, (5) tax reporting costs, (6) license fees, and (7) up to $100,000 per annum in legal fees. The Sponsor has also paid the costs of the Trust’s organization and the initial sales of the Shares, including applicable SEC registration fees.

5 - Related Parties

The Sponsor, the Manager and the Trustee are considered to be related parties to the Trust. The Trustee’s fee is paid by the Sponsor and is not a separate expense of the Trust. The Manager is paid by the Investing Pool and that fee is an indirect expense of the Trust.

6 - Indemnification

The Sponsor and its shareholders, directors, officers, employees, affiliates (as such term is defined under the United States Securities Act of 1933, as amended) and subsidiaries are entitled to be indemnified by the Trust and held harmless against any loss, liability or expense arising out of or in connection with the performance of their obligations under the Trust Agreement or any actions taken in

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

accordance with the provisions of the Trust Agreement and incurred without their (1) negligence, bad faith, willful misconduct or willful malfeasance or (2) reckless disregard of their obligations and duties under the Trust Agreement.

7 - Commitments and Contingent Liabilities

In the normal course of business, the Trust may enter into contracts with service providers that contain general indemnification clauses. The Trust’s maximum exposure under these arrangements is unknown as this would involve future claims that may be made against the Trust that have not yet occurred.

8 - Net Asset Value and Financial Highlights

The Trust is presenting the following net asset values and financial highlights related to investment performance and operations for a Share outstanding for the period from January 1, 2011 to September 30, 2011. The net investment income (loss) and total expense ratios are calculated using average net assets. The net asset value presentation is calculated using daily Shares outstanding. The net investment income (loss) and total expense ratios have been annualized and include the allocation of net investment income (loss) and expenses from the Investing Pool. The total return is based on the change in net asset value of a Share during the period. An investor’s return and ratios may vary based on the timing of capital transactions.

9 - Investment Valuation

In accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 820, Fair Value Measurements and Disclosures, the Trust values investments using a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. Inputs may be based on independent market data (“observable inputs”) or they may be internally developed (“unobservable inputs”). The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows:

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iShares^® S&P GSCI™ Commodity-Indexed Trust

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

Substantially all of the net assets of the Trust consist of its interests in the Investing Pool, which are measured at fair value. Interests in the Investing Pool are classified as Level 2, as there are no active markets for interests in the Investing Pool, while all significant inputs for the value of the Investing Pool are directly observable to the Trust.

At September 30, 2011 and December 31, 2010, the fair value of the Trust’s interests in the Investing Pool equaled $1,263,970,653 and $1,799,879,995, respectively.

Disclosure regarding fair value measurements relating to the Investing Pool’s investment portfolio can be found in Note 10 of the Investing Pool’s Notes to Financial Statements.

10 - Subsequent Events

In connection with the preparation of the financial statements of the Trust as of and for the period ended September 30, 2011, management has evaluated the impact of all subsequent events on the Trust through the date the financial statements were issued and has determined that there were no subsequent events requiring adjustment or disclosure in the financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Statements of Financial Condition

At September 30, 2011 (Unaudited) and December 31, 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Statements of Operations (Unaudited)

For the three and nine months ended September 30, 2011 and 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Statements of Changes in Members’ Equity

For the nine months ended September 30, 2011 (Unaudited)

and the year ended December 31, 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Statements of Cash Flows (Unaudited)

For the nine months ended September 30, 2011 and 2010

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Schedule of Investments (Unaudited)

September 30, 2011

See notes to financial statements.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Notes to Financial Statements (Unaudited)

September 30, 2011

1 - Organization

The iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC (the “Investing Pool”) is a limited liability company organized under the laws of the State of Delaware on July 7, 2006 and commenced operations on July 10, 2006. Prior to May 9, 2007, the Investing Pool was known as the iShares^® GSCI^® Commodity-Indexed Investing Pool LLC. BlackRock Asset Management International Inc. (the “Manager”) is responsible for the administration of the Investing Pool. The Investing Pool holds long positions in futures contracts on the S&P GSCI™ Excess Return Index (“S&P GSCI-ER”) listed on the Chicago Mercantile Exchange (the “CME”) called Commodity Excess Return Futures (“CERFs”) and posts margin in the form of cash or short-term or similar securities, referred to as “Short-Term Securities,” to collateralize its CERF positions.

It is the objective of the Investing Pool that its performance will correspond generally to the performance of the S&P GSCI™ Total Return Index (the “Index”) before payment of the Investing Pool’s expenses.

The Investing Pool is a commodity pool, as defined in the regulations of the Commodity Futures Trading Commission (the “CFTC”) and is operated by the Manager, a commodity pool operator registered with the CFTC. The Manager is an indirect subsidiary of BlackRock, Inc. BlackRock Fund Advisors (the “Advisor”), an indirect subsidiary of BlackRock, Inc., serves as the commodity trading advisor of the Investing Pool and is registered with the CFTC.

The Investing Pool is not an investment company registered under the Investment Company Act of 1940, as amended.

2 - Summary of Significant Accounting Policies

The following is a summary of significant accounting policies consistently followed by the Investing Pool in the preparation of its financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates and these differences could be material.

Certain amounts in the financial statements for the prior year have been reclassified to conform to the current financial statement presentation.

CERFs are futures contracts listed on the CME whose settlement at expiration is based on the value of the S&P GSCI-ER at that time. The terms of the CERFs require the Investing Pool to deposit initial margin with a value equal to 100% of the value of each CERF position at the time the position is established, thereby making those positions unleveraged. Because of this, additional variation margin payments are not required. Although daily variation margins are not required, daily fluctuations in the value of the CERFs are recorded as an unrealized gain or loss. When a CERF is closed, the Investing Pool records a realized gain or loss based on the difference between the value of the CERF at the time it was opened and the value at the time it was closed. The Investing Pool will deposit with the clearing futures commission merchant (“FCM”) the required margin for the CERFs in the form of cash or Short-Term Securities. CERFs are derivative instruments valued at fair value, which the Manager has determined to be that day’s announced CME settlement price for the CERF. If there is no announced CME settlement price for the CERF on that day, the Manager will use the most recently announced CME settlement price unless the Manager determines that the price is inappropriate as a basis for the valuation of the CERFs. The Investing Pool’s investment in the CERFs has not been designated as a hedging instrument. As a result, all changes in the fair value are reflected in the Statements of Operations.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

The investment objective of the Investing Pool is to seek investment results that correspond generally to the performance of the Index before payment of the Investing Pool’s expenses through holdings of long positions in CERFs.

For futures contracts, counterparty credit risk is mitigated because futures contracts are exchange-traded and the exchange’s clearing house acts as central counterparty to all exchange-traded futures contracts (although customers continue to have credit exposure to the clearing member who holds their account).

Please refer to Note 9 for additional disclosures regarding the Investing Pool’s investments in CERFs.

The Investing Pool defines cash and cash equivalents to be highly liquid investments with original maturities of three months or less.

As of September 30, 2011 and December 31, 2010, the Investing Pool had cash and cash equivalents held at its clearing FCM of $39,982,743 and $76,335,484, respectively, which were posted as margin to collateralize its CERF positions.

Short-term investments on the Statements of Financial Condition consist principally of short-term fixed income securities with original maturities of one year or less. These investments are valued at fair value.

As of September 30, 2011 and December 31, 2010, the Investing Pool had short-term investments held at its clearing FCM of $1,253,380,535 and $1,687,824,740, respectively, which were posted as margin to collateralize its CERF positions.

Securities transactions are accounted for on the trade date. Realized gains and losses on investment transactions are determined using the specific identification method. Other income and expenses are recognized on the accrual basis.

The Investing Pool is not an association taxable as a corporation and is treated as a partnership for federal, state and local income tax purposes.

No provision for federal, state, and local income taxes has been made in the accompanying financial statements because the Investing Pool is not subject to income taxes. Holders of interests in the Investing Pool are individually responsible for their own tax payments on their proportionate share of gains, losses, credits, or deductions.

The net asset value of the Investing Pool on any given day is obtained by subtracting the Investing Pool’s accrued expenses and other liabilities on that day from the value of the assets of the Investing Pool, calculated as of 4:15 p.m. (New York time) on each day on which NYSE Arca, Inc. (“NYSE Arca”) is open for regular trading, as soon as practicable after that time.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

In May 2011, the Financial Accounting Standards Board issued amended guidance to improve disclosure about fair value measurements which will require the following disclosures for fair value measurements categorized as Level 3: quantitative information about the unobservable inputs and assumptions used in the fair value measurement, a description of the valuation policies and procedures and a narrative description of the sensitivity of the fair value measurement to changes in unobservable inputs and the interrelationships between those unobservable inputs. In addition, the amounts and reasons for all transfers in and out of Level 1 and Level 2 will be required to be disclosed. The amended guidance is effective for financial statements for fiscal years beginning after December 15, 2011, and interim periods within those fiscal years. Management is evaluating the impact of this guidance on the Investing Pool’s financial statements and disclosures.

3 - Offering of the Investing Pool Interests

Interests in the Investing Pool (“Investing Pool Interests”) are issued only to and redeemable only by the iShares^® S&P GSCI™ Commodity-Indexed Trust (the “Trust”) in exchange for a combination of CERFs and cash or Short-Term Securities in lieu of cash. The baskets of CERFs and cash or Short-Term Securities in lieu of cash are transferred to or from the Trust in exchange for Investing Pool Interests. Individual investors cannot purchase or redeem Investing Pool Interests. The Investing Pool transacts only with the Trust and the Manager.

Redemptions of Investing Pool Interests in exchange for CERFs and cash or Short-Term Securities in lieu of cash are treated as sales for financial statement purposes.

4 - Investing Pool Expenses

The Manager pays the amounts that would otherwise be considered the ordinary operating expenses, if any, of the Investing Pool. The Manager receives an allocation from the Investing Pool that accrues daily at an annualized rate equal to 0.75% of the net asset value of the Investing Pool.

5 - Related Parties

BlackRock Institutional Trust Company, N.A. is the “Administrator” of the Investing Pool. The Manager and the Administrator are considered to be related parties to the Trust and Investing Pool. The Advisor is considered to be a related party to the Investing Pool. The Administrator’s and Advisor’s fees are paid by the Manager from the Investing Pool’s expense allocation to the Manager and are not a separate expense of the Investing Pool.

6 - Indemnification

The Trust, the Manager and any officers, agents and delegates of the Investing Pool (the “Indemnitees”) are entitled to indemnification from the Investing Pool for any loss, damage, claim or expense (including reasonable attorney’s fees) incurred by any Indemnitee by reason of any act or omission performed or omitted by such Indemnitee on behalf of the Investing Pool, unless such act or omission is the result of such Indemnitee’s gross negligence, bad faith or willful misconduct, and provided that such indemnity shall be provided out of, and only to the extent of, the Investing Pool’s assets.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

7 - Commitments and Contingent Liabilities

In the normal course of business, the Investing Pool may enter into contracts with service providers that contain general indemnification clauses. The Investing Pool’s maximum exposure under these arrangements is unknown as this would involve future claims that may be made against the Investing Pool that have not yet occurred.

8 - Financial Highlights

The Investing Pool is presenting the following financial highlights related to investment performance and operations for the period from January 1, 2011 to September 30, 2011. The net investment income (loss) and total expense ratios are calculated using average net assets and have been annualized. The total return is based on the change in the net asset value during the period.

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

9 - Investing in CERFs

Substantially all of the Investing Pool’s assets are invested in CERFs. The CERFs’ settlement value at expiration is based on the value of S&P GSCI-ER at that time. Therefore, the value of the Investing Pool will fluctuate based upon the value of the S&P GSCI-ER and the prices of the commodities underlying the S&P GSCI-ER. The commodities markets have historically been extremely volatile. For the nine months ended September 30, 2011 and the year ended December 31, 2010, the average month-end notional amount of open CERFs were $1,725,029,824 and $1,637,577,662, respectively.

The following table shows the variation margin on open futures contracts, by risk exposure category, on the Statements of Financial Condition for as of September 30, 2011 and December 31, 2010:

The following table shows the effect of the futures contracts, by risk exposure category, on the Statements of Operations for the nine months ended September 30, 2011 and 2010:

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iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC

Notes to Financial Statements (Unaudited) (Continued)

September 30, 2011

10 - Investment Valuation

In accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 820, Fair Value Measurements and Disclosures, the Investing Pool values investments using a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. Inputs may be based on independent market data (“observable inputs”) or they may be internally developed (“unobservable inputs”). The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows:

Investments in CERFs are measured at fair value using CME settlement prices for CERFs. CERFs are classified as Level 1 investments, as CME settlement prices are quoted prices for identical assets in active markets. At September 30, 2011 and December 31, 2010, the fair value of CERFs equaled $1,261,775,360 and $1,798,137,200, respectively.

The terms of the CERFs require the Investing Pool to deposit initial margin with a value equal to 100% of the value of each CERF position at the time the position is established, thereby making those positions unleveraged. This margin collateral, in the form of short-term investments in U.S. Treasury bills, is valued at fair value. U.S. Treasury bills are classified as Level 2 investments, as these trade in markets that are not considered active, but whose values are based on inputs such as quoted market prices, dealer quotations or valuations provided by alternative pricing sources that are supported by observable inputs. At September 30, 2011 and December 31, 2010, the fair value of short-term investments equaled $1,253,380,535 and $1,687,824,740, respectively.

11 - Subsequent Events

In connection with the preparation of the financial statements of the Investing Pool as of and for the period ended September 30, 2011, management has evaluated the impact of all subsequent events on the Investing Pool through the date the financial statements were issued and has determined that there were no subsequent events requiring adjustment or disclosure in the financial statements.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

This information should be read in conjunction with the financial statements and notes to financial statements included in Item 1 of Part I of this Form 10-Q. The discussion and analysis that follows may contain statements that relate to future events or future performance. In some cases, such forward-looking statements can be identified by terminology such as “may,” “should,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “predict,” “potential” or the negative of these terms or other comparable terminology. None of the Trust, the Sponsor, the Manager, the Trustee or the Delaware Trustee assumes responsibility for the accuracy or completeness of any forward-looking statements. None of the Trust, the Sponsor, the Manager, the Trustee or the Delaware Trustee is under a duty to update any of the forward-looking statements to conform such statements to actual results or to a change in expectations or predictions.

Introduction

The iShares^® S&P GSCI™ Commodity-Indexed Trust (the “Trust”) is a Delaware statutory trust that issues units of beneficial interest (“Shares”) representing fractional undivided beneficial interests in its net assets. Substantially all of the assets of the Trust consist of interests in the iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC (the “Investing Pool”). The Investing Pool holds long positions in futures contracts (“CERFs”) on the S&P GSCI™ Excess Return Index (“S&P GSCI-ER”) listed on the Chicago Mercantile Exchange, (the “CME”), and posts margin in the form of cash or short-term or similar securities, referred to as “Short-Term Securities,” to collateralize its CERF positions. It is the objective of the Trust that the performance of the Shares will correspond generally to the performance of the S&P GSCI™ Total Return Index (the “Index”) before payment of the Trust’s and the Investing Pool’s expenses and liabilities. The Index is intended to reflect the performance of a diversified group of commodities. BlackRock Asset Management International Inc. (“BAMII”) is the “Sponsor” of the Trust and the “Manager” of the Investing Pool. BlackRock Institutional Trust Company, N.A. is the “Trustee” of the Trust. The Trust and the Investing Pool are commodity pools, as defined in the regulations of the Commodity Futures Trading Commission (the “CFTC”) and are operated by BAMII, a commodity pool operator registered with the CFTC. The Trust and the Investing Pool have delegated some of the administration to State Street Bank and Trust Company (the “Trust Administrator” or “Investing Pool Administrator”). Wilmington Trust Company, a Delaware banking corporation, serves as the “Delaware Trustee” of the Trust. Neither the Trust nor the Investing Pool is an investment company registered under the Investment Company Act of 1940, as amended.

The Trust intends to offer Shares on a continuous basis but is not required to do so and may suspend the offering of Shares at any time. The Trust issues and redeems Shares only in one or more blocks of 50,000 Shares (“Baskets”). These transactions are generally in exchange for consideration (or redemption proceeds) consisting of CERFs and cash (or, at the discretion of the Sponsor, Short-Term Securities in lieu of cash) with a value equal to the net asset value per Basket on the date the creation or redemption order is received in proper form. Only certain institutions, called “Authorized Participants,” that enter into an agreement with the Trust may purchase or redeem Baskets. Owners of beneficial interests in Shares (“Shareholders”) who are not Authorized Participants have no right to redeem their Shares; they may redeem their Shares only through an Authorized Participant and only in Baskets.

Shares of the Trust trade on NYSE Arca under the symbol “GSG.”

Valuation of CERFs; Computation of Trust’s Net Asset Value

The Trustee determines the net asset value of the Trust and the net asset value per Share, or NAV, as of 4:15 p.m. (New York time), on each business day on which NYSE Arca is open for regular trading, as soon as practicable after that time. The Trustee values the Trust’s assets based upon the determination by the Manager, which may act through the Investing Pool Administrator, of the net asset value of the Investing Pool. The Manager determines the net asset value of the Investing Pool as of the same time that the Trustee determines the net asset value of the Trust.

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The Manager values the Investing Pool’s long position in CERFs on the basis of that day’s announced CME settlement price for the CERF. The value of the Investing Pool’s CERF position (including any related margin) equals the product of (a) the number of CERF contracts owned by the Investing Pool and (b) the settlement price on the date of calculation. If there is no announced CME settlement price for the CERF on a business day, the Manager uses the most recently announced CME settlement price unless the Manager determines that such price is inappropriate as a basis for valuation. The daily settlement price for the CERF is established by the CME shortly after the close of trading in Chicago on each trading day.

The Manager values all other property of the Investing Pool at (a) its current market value, if quotations for such property are readily available, or (b) its fair value, as reasonably determined by the Manager, if the current market value cannot be determined.

Once the value of the CERFs and interest earned on any assets posted as margin and any other assets of the Investing Pool has been determined, the Manager subtracts all accrued expenses and liabilities of the Investing Pool as of the time of calculation in order to calculate the net asset value of the Investing Pool. The Manager, or the Investing Pool Administrator on its behalf, then calculates the value of the Trust’s interests in the Investing Pool (“Investing Pool Interests”) and provides this information to the Trustee.

Once the value of the Trust’s Investing Pool Interests has been determined and provided to the Trustee, the Trustee subtracts all accrued expenses and other liabilities of the Trust from the total value of the assets of the Trust, in each case as of the calculation time. The resulting amount is the net asset value of the Trust. The Trustee determines the NAV by dividing the net asset value of the Trust by the number of Shares outstanding at the time the calculation is made. Shares to be delivered under a creation order are considered to be outstanding for purposes of determining the NAV if the applicable creation order was received by the Trustee prior to 2:40 p.m. (New York time) (or, on any day on which the CME is scheduled to close early, prior to the close of trading of CERFs on the CME on such day), on the date of calculation. Shares to be delivered under a redemption request are not considered to be outstanding for purposes of calculating the NAV if the applicable redemption request was received by the Trustee prior to 2:40 p.m. (New York time) (or, on any day on which the CME is scheduled to close early, prior to the close of trading of CERFs on the CME on such day), on the date of calculation.

Results of Operations

The Quarter Ended September 30, 2011

The Trust’s net asset value decreased from $1,523,113,488 at June 30, 2011 to $1,263,970,653 at September 30, 2011. The decrease in the Trust’s net asset value was primarily due to a decrease in outstanding Shares, which fell from 44,700,000 at June 30, 2011 to 41,650,000 at September 30, 2011 due to 400,000 Shares (8 Baskets) being created and 3,450,000 Shares (69 Baskets) being redeemed during the quarter. The Trust’s net asset value was also affected by a decrease in the price of CERFs during the quarter from $487.90 at June 30, 2011 to $435.20 at September 30, 2011, a 10.80% decrease.

The Nine Months Ended September 30, 2011

The Trust’s net asset value decreased from $1,799,879,995 at December 31, 2010 to $1,263,970,653 at September 30, 2011. The decrease in the Trust’s net asset value was primarily due to a decrease in outstanding Shares, which fell from 52,700,000 at December 31, 2010 to 41,650,000 at September 30, 2011 due to 2,600,000 Shares (52 Baskets) being created and 13,650,000 Shares (273 Baskets) being redeemed during the period. The Trust’s net asset value was also affected by a decrease in the price of the March 2014 CERFs from the average purchase price of $501.91 to $435.20 at September 30, 2011, a 13.29% decrease.

This decrease in the Trust’s net asset value was partially offset when in February 2011, the Investing Pool began trading in CERFs expiring in March 2014 in connection with the rolling process from CERFs expiring in March 2011. The March 2011 CERFs

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increased in price from $480.40 at December 31, 2010 to a final sale price of $510.80 in February 2011, a 6.33% increase. For the period ended September 30, 2011, the Trust had a net realized gain on futures contracts of $173,197,510 and brokerage commissions and fees of $759,846 allocated from the Investing Pool primarily in connection with the rolling process.

Liquidity and Capital Resources

The Trust’s sole asset as of September 30, 2011 was its investment in the Investing Pool. The Investing Pool’s assets consist of CERFs, cash and Short-Term Securities that are posted as collateral for the Investing Pool’s CERF positions. The Trust and the Investing Pool do not anticipate any further need for liquidity because creations and redemptions of Shares generally occur in kind and ordinary expenses are met by cash on hand. Interest earned on the assets posted as collateral is paid to the Investing Pool and is used to pay the fixed fee to the Manager and purchase additional CERFs, or, in the discretion of the Sponsor, distributed to Shareholders. In exchange for a fee based on the net asset value of the Investing Pool, the Sponsor and the Manager have assumed most of the ordinary expenses incurred by the Trust and the Investing Pool. In the case of an extraordinary expense and/or insufficient interest income to cover ordinary expenses, however, the Investing Pool could be forced to liquidate its CERF positions to pay such expenses. As of September 30, 2011, the market for CERFs had not developed significant liquidity and the Investing Pool represented substantially all of the long-side open interest in CERFs. In addition, it is expected that Goldman, Sachs & Co. or its accountholders may represent, directly or indirectly, a substantial portion of the short-side interest in such market. The existence of such a limited number of market participants could cause or exacerbate losses to the Trust if the Trust were required to liquidate its CERF positions.

The Sponsor is unaware of any other trends, demands, conditions or events that are reasonably likely to result in material changes to the Trust’s or the Investing Pool’s liquidity needs.

Because the Investing Pool trades CERFs, its capital is at risk due to changes in the value of the CERFs or other assets (market risk) or the inability of counterparties to perform (credit risk).

Market Risk

The Investing Pool holds CERF positions and posts cash and Short-Term Securities as margin to collateralize the CERF positions. Because of this limited diversification of the Investing Pool’s assets, fluctuations in the value of the CERFs are expected to directly affect the value of the Shares. The value of the CERFs is expected to track generally the S&P GSCI-ER, although this correlation may not be exact. The S&P GSCI-ER, in turn, reflects the value of a diversified group of commodities. The market risk associated with the Investing Pool’s CERF positions is limited to the amount of cash and Short-Term Securities posted as margin. The Investing Pool’s exposure to market risk will be influenced by a number of factors, including the lack of liquidity of the CERF market and activities of other market participants.

Credit Risk

When the Investing Pool purchases or holds CERFs, it is exposed to the credit risk of a default by the CME Clearing House, which serves as the counterparty to each CERF position, and of a default by its clearing futures commission merchant. In the case of such a default, the Investing Pool could be unable to recover amounts due to it on its CERF positions and assets posted as margin. The Investing Pool is also exposed to the credit risk of the obligors of any Short-Term Securities posted as margin.

Off-Balance Sheet Arrangements and Contractual Obligations

The Trust and the Investing Pool have not used, nor do they expect to use, special purpose entities to facilitate off-balance sheet financing arrangements. The Trust and the Investing Pool have no loan guarantee arrangements or other off-balance sheet arrangements of any kind other than agreements entered into in the normal course of business, which may include indemnification

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provisions related to certain risks service providers undertake in performing services that are in the interest of the Trust and the Investing Pool. While the Trust’s and the Investing Pool’s exposure under such indemnification provisions cannot be estimated, these general business indemnifications are not expected to have a material impact on either the Trust’s or the Investing Pool’s financial position.

Critical Accounting Policies

The financial statements and accompanying notes are prepared in accordance with accounting principles generally accepted in the United States of America. The preparation of these financial statements relies on estimates and assumptions that impact the Trust’s and the Investing Pool’s financial position and results of operations. These estimates and assumptions affect the Trust’s and the Investing Pool’s application of accounting policies. In addition, please refer to Note 2 to the financial statements of the Trust and the Investing Pool for further discussion of the Trust’s and the Investing Pool’s accounting policies.

Item 3. Quantitative and Qualitative Disclosures About Market Risk

Quantitative Disclosure

The Trust and Investing Pool are exposed to commodity price risk through the Investing Pool’s holdings of CERFs. The following table provides information about the Investing Pool’s futures contract positions, which are sensitive to changes in commodity prices. As of September 30, 2011, the Investing Pool’s open CERF positions (long) were as follows:

The notional amount is calculated using the settlement price for the CERFs on the CME on September 30, 2011, which was $435.20 per contract, and the $100 multiplier applicable under the contract terms.

Qualitative Disclosure

As described herein, it is the objective of the Trust, through its investment in the Investing Pool, that the performance of the Shares will correspond generally to the performance of the Index, before payment of expenses and liabilities. The Index itself is intended to reflect the performance of a diversified group of physical commodities, including energy commodities, precious and industrial metal commodities, agricultural commodities and livestock commodities. The Trust obtains this exposure to commodity prices through the Investing Pool’s CERF positions. As a result, fluctuations in the value of the CERFs are expected to directly affect the value of the Shares.

Neither the Trust nor the Investing Pool will engage in any activities designed to obtain a profit from, or ameliorate losses caused by, changes in the value of the CERFs, any commodities underlying the Index or the S&P GSCI-ER, or any assets posted as margin. Because of the 100% margin requirement applicable to the Investing Pool’s CERF positions, the market risk associated with the Investing Pool’s CERF position is limited to the amount of cash and Short-Term Securities posted as margin. The Investing Pool’s exposure to market risk may be influenced by a number of factors, including the lack of liquidity of the CERF market and activities of other market participants.

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Item 4. Controls and Procedures

The duly authorized officers of the Sponsor and Manager performing functions equivalent to those a principal executive officer and principal financial officer of the Trust and the Investing Pool would perform if the Trust and the Investing Pool had any officers, and with the participation of the Trustee and the Investing Pool Administrator, have evaluated the effectiveness of the Trust’s and Investing Pool’s disclosure controls and procedures, and have concluded that the disclosure controls and procedures of the Trust and the Investing Pool were effective as of the end of the period covered by this report to provide reasonable assurance that information required to be disclosed in the reports that the Trust and the Investing Pool file or submit under the Securities Exchange Act of 1934, as amended, is recorded, processed, summarized and reported, within the time periods specified in the applicable rules and forms, and that it is accumulated and communicated to the duly authorized officers of the Sponsor and Manager performing functions equivalent to those a principal executive officer and principal financial officer of the Trust and the Investing Pool would perform if the Trust and the Investing Pool had any officers, as appropriate to allow timely decisions regarding required disclosure.

There are inherent limitations to the effectiveness of any system of disclosure controls and procedures, including the possibility of human error and the circumvention or overriding of the controls and procedures.

There were no changes in the Trust’s and Investing Pool’s internal control over financial reporting that occurred during the period covered by this report that have materially affected, or are reasonably likely to materially affect, the Trust’s and Investing Pool’s internal control over financial reporting.

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PART II – OTHER INFORMATION

Item 1. Legal Proceedings

None.

Item 1A. Risk Factors

There have been no material changes to the Risk Factors last reported under Part I, Item 1A of the registrants’ Annual Report on Form 10-K for the year ended December 31, 2010, filed with the Securities and Exchange Commission on February 25, 2011, except for the following changes, which were included in the prospectus filed with the Securities and Exchange Commission on October 25, 2011 pursuant to Rule 424(b)(3) of the Securities Act of 1933, as amended:

(1)        The risk factor entitled “Commodity futures trading may be illiquid. In addition, suspensions or disruptions of market trading in the commodities markets and related futures markets may adversely affect the value of your Shares” was modified by adding two sentences to the end of the first paragraph of the risk factor (and making related conforming changes within the risk factor). This risk factor now reads as follows:

The commodity futures markets are subject to temporary distortions or other disruptions due to various factors, including the lack of liquidity, congestion, disorderly markets, limitations on deliverable supplies, the participation of speculators, government regulation and intervention, technical and operational or system failures, nuclear accidents, terrorism, riots and acts of God. In addition, U.S. futures exchanges and some foreign exchanges have regulations that limit the amount of fluctuation in futures contract prices that may occur during a single business day. These limits are generally referred to as “daily price fluctuation limits,” and the maximum or minimum price of a contract on any given day as a result of these limits is referred to as a “limit price.” Once the limit price has been reached in a particular contract, it is possible that no trades may be made at a different price. It is not certain how long any such price limits would remain in effect. Limit prices may have the effect of precluding trading in a particular contract or forcing the liquidation of contracts at disadvantageous times or prices, consequently affecting the value of the S&P GSCI-ER. Further, it is expected that Goldman, Sachs & Co. or its account holders may represent, directly or indirectly, a substantial portion of the short-side interest in the CERFs market. The existence of such a limited number of market participants could cause or exacerbate temporary distortions, especially those distortions resulting from illiquidity.

Any of these circumstances could thereby adversely affect the value of the CERFs held by the Investing Pool and, therefore, the value of your Shares. In addition, these circumstances could also limit trading in the CERFs, which could affect the calculation of the NAV and the trading price of the Shares. Accordingly, these limits may result in an NAV that differs, and may differ significantly, from the NAV that would prevail in the absence of such limits. If Baskets are created or redeemed at a time when these price limits are in effect, the creation or redemption price will reflect the price limits as well.

In calculating the S&P GSCI-ER, if the relevant trading facility does not publish a settlement price as scheduled, or publishes a settlement price that, in the reasonable judgment of the Index Sponsor, is manifestly incorrect, the Index Sponsor may determine the settlement price in its reasonable judgment. In addition, if any day on which the Index Sponsor calculates the S&P GSCI-ER is a day on which a relevant trading facility for a contract on a commodity that underlies the S&P GSCI-ER is not open, then the Index Sponsor will use the settlement price for that contract as of the last day on which that trading facility was open. In these circumstances, the value of the CERFs and the value of your Shares may be adversely affected.

(2)        The risk factor entitled “Regulatory developments with respect to the futures and over-the-counter derivatives markets, and in particular, with respect to speculative trading in futures contracts and over-the-counter derivatives involving commodities and commodity indices, could adversely affect the value of your Shares” was modified (a) by adding or revising the last two sentences of

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the fifth paragraph and (b) by adding a new ninth paragraph (and, in each case, making related conforming changes within the risk factor), so that the risk factor now reads as follows:

A number of bills have been introduced in the U.S. Congress in response to high energy and commodity prices. These bills generally target perceived excessive speculation in commodities and commodity indices, including by institutional “index funds,” on regulated futures markets and in the over-the-counter (“OTC”) derivatives markets. These bills include a broad range of measures intended to limit speculation, including possible increases in the margin levels required for regulated futures contracts; imposing, or tightening existing, speculative position limits applicable to regulated futures and over-the-counter derivatives positions; transferring from U.S. futures exchanges to the CFTC the authority to establish certain speculative position limits; imposing aggregate speculative position limits across regulated futures, over-the-counter positions and certain contracts traded on non-U.S. exchanges; eliminating or narrowing existing exemptions from speculative position limits; restricting the access of certain classes of investors to futures markets and over-the-counter derivatives markets; and imposing additional reporting requirements on market participants, such as the Investing Pool.

Some of the measures have not been adopted but could be in the future. Some of these measures have been adopted in the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”), which was signed into law on July 21, 2010. Under the Dodd-Frank Act, the CFTC is required to establish speculative position limits on listed futures and options on physical commodities (including certain energy, metals and agricultural products) and economically equivalent OTC derivatives. The Dodd-Frank Act also requires the CFTC to establish aggregate position limits for contracts based on the same underlying commodity, including certain contracts traded on non-U.S. exchanges and economically equivalent OTC derivatives. The Dodd-Frank Act also significantly narrows the availability of the bona fide hedging exemptions applicable to contracts in such physical commodities to a narrower category of commercial market participants and physical hedging strategies. Although the CFTC may exempt persons, contracts or transactions or classes thereof from the speculative position limit requirements, regulatory action pursuant to the Dodd-Frank Act may impose new limitations on the size of positions that may be taken with respect to CERFs, or on the size of positions that may be carried by the Investing Pool’s Clearing FCM. Such position limits may adversely affect the value of the Shares or liquidity in the market for them.

Pursuant to the statutory mandate described above, the CFTC proposed regulations in January 2011 (the “2011 Proposed Rules”) that would, among other proposed changes, impose new federal position limits on futures and options on a subset of energy, metal, and agricultural commodities (“referenced contracts”) and economically equivalent swaps. The referenced contracts subject to the 2011 Proposed Rules represent over 50% of the S&P GSCI-ER. In addition, under the 2011 Proposed Rules, any risk management exemptions granted by designated contract markets (“DCMs”), such as the exemption applicable to the Investing Pool’s position in CERFs, would be subject to CFTC review and approval. As a result, if the 2011 Proposed Rules are adopted as proposed, the size of the maximum position in CERFs permitted to be held by the Investing Pool could be significantly reduced, which could in turn require the Investing Pool to liquidate some or all of its position in CERFs. Any such reduction could adversely affect the value of the Shares.

The 2011 Proposed Rules would also expand the circumstances requiring certain persons to aggregate listed futures and economically equivalent swap positions owned or controlled by such persons. The proposed aggregation standards would require, if adopted, certain investors in the Trust to aggregate Investor Pool positions in CERFs with other positions in CERFs or

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other contracts subject to aggregation with CERFs. These proposed measures, if adopted, could directly reduce liquidity in CERFs and the futures contracts and commodities underlying the S&P GSCI-ER, adversely affecting the value of the Shares.

The 2011 Proposed Rules would further narrow the existing bona fide hedge exemption for referenced futures contracts and significantly narrow the risk management exemption relief from speculative position limits currently permitted to be granted for transactions in listed futures and options offsetting risks arising from over-the-counter swap positions. These proposed measures could affect the hedging and investing activities of participants in the markets for the CERFs and the futures contracts and commodities underlying the S&P GSCI-ER, which in turn could reduce the liquidity and adversely affect the pricing of the CERFs and such futures contracts and commodities. These risks are particularly acute given that there are expected to be only a limited number of participants in the market for CERFs. Any of these effects could increase volatility in and otherwise adversely affect the price of the Shares.

Additionally, the Commission may further lower the applicable position limits, apply position limits to a broader range of contracts (including commodity index contracts) and further restrict position limit exemptions. Any such measures could further reduce the size of positions that the Investing Pool and other investors could hold directly in CERFs and the underlying futures and commodities, with potential reductions in liquidity and adverse effects on the pricing of CERFs. See also “Risk Factors—The value of the Shares depends on the value of CERFs, which will fluctuate based on the prices of commodity futures contracts reflected in the S&P GSCIER. These prices may be volatile, thereby creating the potential for losses, regardless of the length of time you intend to hold your Shares.”

On December 22, 2010, the CFTC proposed rules (the “DCM Proposed Rules”) that would require that at least 85% of the total volume of any contract listed on a DCM, including CERFs listed on the CME, be executed through the central order book, rather than as a block transaction or other non-competitively executed transaction. Contracts that do not meet the 85% threshold would be required to be delisted by the DCM and transferred to a swap execution facility or liquidated.

Generally, the Investing Pool’s transactions in CERFs have been executed through block or “exchange of futures for physicals” transactions that are not executed through the CME’s central order book. While subject to revision by the CFTC in response to public comment, this provision of the DCM Proposed Rules could, if adopted as proposed, significantly and adversely affect the availability, liquidity and price of CERFs, as well as futures contracts currently included or which may in the future be included in the S&P GSCI-ER, and could inhibit the Trust’s ability to redeem and offer Shares, which in turn could adversely affect the value and continued availability of the Shares.

On August 1, 2011, the CFTC proposed rules (the “FCM Proposed Rules”) regarding the risk management practices of clearing members, which would require the Investing Pool’s Clearing FCM to establish risk-based limits on position and order size, amongst other measures. If adopted as proposed, the FCM Proposed Rules may lead the Investing Pool’s Clearing FCM to reduce its internal limits on the size of the CERF positions it will execute or clear for the Investing Pool, reducing the Investing Pool’s and other market participants’ ability to transact in CERFs, and potentially adversely affecting the price of Shares. In the event that the Investing Pool’s Clearing FCM does reduce its internal limits on the size of CERF positions, the Investing Pool may deem it feasible to use additional clearing FCMs. If this happens, it could substantially increase the costs of clearing for the Investing Pool.

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Other regulatory measures under the Dodd-Frank Act could increase the costs of the Investing Pool, result in significant direct limitations on the maximum permitted size of the Investing Pool’s futures positions and therefore on the size of the Trust, or affect liquidity in the market for the CERFs or the underlying futures contracts, as well as the correlation between the price of the Shares and the net asset value of the Trust. While it is impossible to predict which measures will be adopted or precisely how they will ultimately affect the value of your Shares, any such measures could adversely affect the value of your Shares.

From August 24, 2009 to April 26, 2010, the Trust suspended the issuance of new Baskets because it could not invest the proceeds of such issuances in additional CERF positions due to restrictions on speculative position limits imposed by the CME.

(3)        The risk factor entitled “The trading of various CERFs – the sole futures contracts traded by the Investing Pool – presents risks unrelated to the S &P GSCI-ER that could adversely affect the value of your Shares” was modified throughout to read as follows:

The impact of the following considerations may be heightened because of the concentration of the Investing Pool’s assets in CERFs. The Investing Pool will not be able to avoid these risks by diversifying into other assets or contracts.

Substantially all of the assets of the Investing Pool will be allocated to the trading of CERFs, and the Investing Pool will not trade any other futures contracts. CERFs have a limited trading history. Until February 2011, only one CERF contract was held by the Investing Pool. That CERF, first listed in March 2006, expired in March 2011. In October 2010 the CME listed a new CERF with an expiration of March 2014. The Investing Pool began purchasing the CERF expiring in March 2014 in February 2011. The Investing Pool has completed its “roll” of the CERFs which expired in March 2011 into CERFs that expire in March 2014. There can be no assurance as to the size or liquidity of the market for CERFs. Illiquidity of the market for CERFs may adversely affect the price of CERFs, the Trust’s ability to track the Index and the Trust’s ability to create or redeem Shares. There can be no assurance that the Clearing FCM, any Authorized Participants or any other market participant will make a market or otherwise trade in CERFs at any time or continue to do so. Withdrawal from the market of any participants, or reduced participation by those persons (especially as there are expected to be only a limited number of participants in the market for CERFs), may reduce the liquidity of CERFs and, accordingly, adversely affect the Shareholders. These risks may be heightened if the Investing Pool’s CERF positions represent a substantial portion of the long-side open interest in the CERFs, as they historically have been. As of June 30, 2011, the market for CERFs had not developed significant liquidity and the Investing Pool represented substantially all of the long-side open interest in CERFs. In addition, it is expected that Goldman, Sachs & Co. or its accountholders will represent, directly or indirectly, a substantial portion of the short-side interest in such market. The existence of such a limited number of market participants could cause or exacerbate losses to the Trust if the Trust were required to liquidate its CERF positions. The longer duration of the CERFs is also not traditional for futures contracts and may affect their liquidity and trading dynamics, which may in turn adversely affect the Shares. In particular, the rolling of each CERF contract, as it approaches expiration, could exacerbate any adverse impacts of illiquidity in the market.

Although CERFs are based on the S&P GSCI-ER, the value of the CERFs and the level of the S&P GSCI-ER may not be equivalent at all times. The CERFs currently purchased by the Investing Pool expire in March of 2014; accordingly, the price at which the CERFs will trade would be expected to correspond to the implied level of the S&P GSCI-ER in March of 2014, not to its current level. Moreover, because the expiration date of the CERFs will differ from the expiration date of the futures contracts

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underlying the S&P GSCI-ER, changes to the value of those futures contracts and, consequently, to the level of the S&P GSCI-ER, will not necessarily result in an equivalent change in the value of the CERFs. In addition, although the current level of the S&P GSCI-ER is expected to influence the implied forward level of the S&P GSCI-ER, other factors, such as the expected rate of inflation, implied interest and yield rates in the market generally and implied volatility may influence market expectations at any given time about prospective changes in the level of the S&P GSCI-ER and consequently the price at which the CERFs trade.

It is also possible that the value of CERFs could be affected by factors that do not directly affect the current or implied forward level of the S&P GSCI-ER, such as the activities of market participants in trading CERFs, or in trading other instruments indexed to the S&P GSCI-ER, as well as supply and demand in the market for such CERFs. Actions by the CME with respect to CERFs, such as the imposition of trading or price limits or a suspension of trading in response to volatile market activity or other causes, and systems or communications failures could also cause the value of the CERFs to diverge from the level of the S&P GSCI-ER.

Although arbitrage activity by market participants is expected to have the effect of reducing or eliminating divergence between the value of the CERFs and the level of the S&P GSCI-ER, such arbitrage activity may not fully offset any divergence at all times during which the Shares are outstanding, especially if the market for the Shares remains illiquid. In the event that such a divergence exists from time to time, changes in the NAV, which is calculated based on the value of the CERFs, will not adequately reflect changes in the level of the S&P GSCI-ER, which could adversely affect the value of the Shares.

In addition, because CERFs are cleared through the CME Clearing House, and the Investing Pool’s CERF positions are carried on its behalf by the Clearing FCM, the Investing Pool, and therefore the Trust, will be subject to the risk of a default by the CME Clearing House or the Clearing FCM. In that event, the Investing Pool, and therefore the Trust, could be unable to recover amounts due to it on its CERF positions, including assets posted as margin, and could sustain substantial losses, even if the level of the S&P GSCI-ER increases. The magnitude of the losses may be significantly increased by the requirement to post 100% margin.

(4)        The risk factor entitled “The Investing Pool’s Clearing FCM or the CME Clearing House could fail, which could expose the Investing Pool to greater risk” was modified by the addition of a third paragraph, so that the risk factor now reads as follows:

The Investing Pool must deposit as margin an amount equal to 100% of the value of the CERFs that it enters into on the date the position is established. In addition, the Clearing FCM is required to deliver or pledge to the CME Clearing House 100% of the value of each CERF it carries on behalf of the Investing Pool. Under the rules of the CME, the CME will have the right to apply assets transferred or pledged to the CME by the Clearing FCM to satisfy certain of the Clearing FCM’s obligations in the event of a default by the Clearing FCM.

As explained elsewhere in this prospectus, this 100% margin requirement is substantially different from the initial margin requirements applicable to most other futures contracts, which are typically 3% to 7% of the value of the relevant contract. As a result, a greater percentage of the assets of the Investing Pool will be held by the Clearing FCM and held by or pledged to the CME Clearing House than would be the case if the Investing Pool entered into other types of futures contracts. In the event of the bankruptcy of the Clearing FCM or the CME Clearing House, therefore, the Investing Pool could be exposed to a risk of loss with respect to a greater portion of its assets. If such a bankruptcy were to occur, the Investing Pool should be afforded the

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protections granted to customers of an FCM, and participants to transactions cleared through an exchange clearing house, under the United States Bankruptcy Code and applicable CFTC regulations. Because such provisions generally provide for a pro rata distribution to customers of customer property held by the bankrupt FCM or clearing house if the customer property held by the FCM or clearing house is insufficient to satisfy the customer claims, the Investing Pool may be disproportionately affected by such a bankruptcy as compared to other customers because the Investing Pool has provided a significantly higher level of margin than have other customers. In any case, there can be no assurance that these protections will be effective in allowing the Investing Pool to recover all, or even any, of the amounts it has deposited as initial margin.

Bankruptcy of the Investing Pool’s Clearing FCM can be caused by, among other things, the default of one of the Clearing FCM’s customers. In this event, the CME Clearing House is permitted to use the entire amount of margin posted by the Investing Pool (as well as margin posted by other customers of the Clearing FCM) to cover the amounts owed by the bankrupt Clearing FCM. Because the Investing Pool deposits 100% margin, it may be disproportionately affected by such a bankruptcy as compared to the other customers of its Clearing FCM.

(5)        The risk factor entitled “Fees and expenses payable by the Investing Pool are charged regardless of profitability and may result in a depletion of resources” was modified by the addition of a second paragraph, so that the risk factor now reads as follows:

The Investing Pool is subject to the fees and expenses described in this prospectus, which are payable irrespective of profitability. These fees and expenses include an allocation to the Manager that accrues daily at an annualized rate equal to 0.75% of the net asset value of the Investing Pool and is payable by the Investing Pool monthly in arrears.

Interest earned on the assets posted as collateral is paid to the Investing Pool and is used to pay the fixed fee to the Manager. A prolonged decline in interest rates could materially affect the amount of interest paid to the Investment Pool. In the case of either an extraordinary expense and/or insufficient interest income to cover ordinary expenses, the Investing Pool could be forced to liquidate its CERF positions to pay such expenses.

(6)        The risk factor entitled “The Shares may not provide anticipated benefits of diversification from other asset classes” was modified by revising the third and fifth sentences of this risk factor. The risk factor now reads as follows:

Historically, the performance of physical commodity futures prices generally has not been correlated to the performance of financial asset classes, such as stocks and bonds. Non-correlation means that there is no statistically significant relationship, positive or negative, between the past performance of futures contracts on physical commodities, on the one hand, and stocks or bonds, on the other hand. Despite this lack of correlation, Shares cannot be expected to be automatically profitable during unfavorable periods for the stock or bond markets, or automatically unprofitable during favorable periods for the stock or bond markets. The commodity futures markets are fundamentally different from the securities markets in that for every gain in commodity futures trading, there is an equal and offsetting loss. The performance of the Shares may reflect positive or negative correlation to one or more financial asset classes, in which case any investment strategy relying on the absence of any such correlation may not be successful.

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(7)        The risk factor entitled “Proprietary trading and other activities by Goldman, Sachs & Co. and its affiliates could conflict with your interests as a Shareholder” was modified by revising the third sentence of the first paragraph of this risk factor. The risk factor now reads as follows:

Activities conducted by Goldman, Sachs & Co. and its affiliates may conflict with your interests as a Shareholder. For example, the Advisor may execute a substantial amount, and potentially all, of the purchases and sales of CERFs through Goldman, Sachs & Co., as the Investing Pool’s Clearing FCM. In addition, it is expected that Goldman, Sachs & Co. or its accountholders will represent, directly or indirectly, a substantial portion of the short-side market for CERFs. Further, Goldman, Sachs & Co. and its affiliates actively trade futures contracts and options on futures contracts on the commodities that underlie the S&P GSCI™, over-the-counter contracts on these commodities, the underlying commodities included in the S&P GSCI™ and other instruments and derivative products based on the S&P GSCI™ and the S&P GSCI-ER. Any of these activities of Goldman, Sachs & Co. or its affiliates could adversely affect the level of the S&P GSCI-ER or CERFs, directly or indirectly, by affecting the price of the underlying commodities and, therefore, the value of the S&P GSCI-ER, CERFs and the price of the Shares.

Goldman, Sachs & Co. and its affiliates may also issue or underwrite other securities or financial or derivative instruments with returns indexed to the S&P GSCI™, the S&P GSCI-ER or the Index, which would compete with the Shares. By introducing competing products into the marketplace, Goldman, Sachs & Co. and its affiliates could adversely affect the price of the Shares. To the extent that Goldman, Sachs & Co. or its affiliates serve as issuer, agent or underwriter of those securities or other similar instruments, their interests with respect to those products may be adverse to your interests as a Shareholder.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

a) None.

b) Not applicable.

c) 3,450,000 Shares (69 Baskets) were redeemed during the quarter ended September 30, 2011.

Item 3. Defaults Upon Senior Securities

None.

Item 5. Other Information

None.

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Item 6. Exhibits

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant and Co-Registrant have duly caused this report to be signed on their behalf by the undersigned in the capacities* indicated, thereunto duly authorized.

BlackRock Asset Management International Inc.

Sponsor of the iShares^® S&P GSCI™ Commodity-Indexed Trust (Registrant)

Manager of the iShares^® S&P GSCI™ Commodity-Indexed Investing Pool LLC (Co-Registrant)

Date: November 8, 2011

Date: November 8, 2011

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