Proto Labs Inc - Quarter Report: 2021 September (Form 10-Q)

PART I. FINANCIAL INFORMATION

Item 1. Financial Statements

The accompanying notes are an integral part of these consolidated financial statements.

Note 1 – Basis of Presentation

The unaudited interim Consolidated Financial Statements of Proto Labs, Inc. (Protolabs, the Company, we, us or our) have been 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 to Form 10-Q and Article 10 of Regulation S-X. In the opinion of management, the accompanying financial statements reflect all adjustments necessary for a fair presentation of the Company’s statements of financial position, results of operations and cash flows for the periods presented. Except as otherwise disclosed herein, these adjustments consist of normal, recurring items. Operating results for interim periods are not necessarily indicative of results that may be expected for the fiscal year as a whole.

The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses, and the related disclosures at the date of the financial statements and during the reporting period. Actual results could materially differ from these estimates. For further information, refer to the audited Consolidated Financial Statements and Notes thereto included in the Company’s Annual Report on Form 10-K for the year ended  December 31, 2020 as filed with the Securities and Exchange Commission (SEC) on February 19, 2021.

The accompanying Consolidated Balance Sheet as of December 31, 2020 was derived from the audited Consolidated Financial Statements but does not include all disclosures required by U.S. GAAP for a full set of financial statements. This Form 10-Q should be read in conjunction with the Company’s Consolidated Financial Statements and Notes included in the Annual Report on Form 10-K filed on February 19, 2021 as referenced above.

Note 2 – Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In December 2019, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12). ASU 2019-12 attempts to simplify aspects of accounting for franchise taxes and enacted changes in tax laws or rates, and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods within that fiscal year. The Company adopted ASU 2019-12 on January 1, 2021 and there was no material impact on the Company’s consolidated financial statements.

Note 3 – Net Income per Common Share

Basic net income per share is computed based on the weighted-average number of common shares outstanding. Diluted net income per share is computed based on the weighted-average number of common shares outstanding, increased by the number of additional shares that would have been outstanding had potentially dilutive common shares been issued and reduced by the number of shares the Company could have repurchased from the proceeds from issuance of the potentially dilutive shares. Potentially dilutive shares of common stock include stock options, restricted stock units and restricted stock awards granted under stock-based compensation plans and shares committed to be purchased under the employee stock purchase plan. Performance stock units are excluded from the calculation of dilutive potential common shares until the performance conditions have been satisfied.

The table below sets forth the computation of basic and diluted net income per share:

Note 4 – Business Combinations

On January 22, 2021, the Company acquired all of the outstanding shares of 3D Hubs, Inc. (Hubs), for $294.1 million, consisting of $127.4 million in cash and 863,995 shares of the Company's common stock valued at $166.7 million on the date of close. Up to an additional $52.8 million of contingent consideration is payable after closing, subject to the satisfaction of performance-based targets during fiscal year 2021 and fiscal year 2022, consisting of up to $25.0 million in cash and up to 143,983 shares of the Company's common stock valued at $27.8 million on the date of close.

Hubs is based in Amsterdam, Netherlands and is a leading online manufacturing platform that provides customers with on-demand access to a global network of premium manufacturing partners. The acquisition enhances the Company’s value proposition by expanding the customer offerings, enabling the Company to more holistically serve its customers.

The fair value of the consideration paid for this acquisition has been allocated on a preliminary basis to the assets purchased and liabilities assumed based on their estimated fair values as of the acquisition date, with any excess recorded as goodwill.  The goodwill associated with the acquisition represents both the strategic and growth opportunities by significantly expanding the customer offering with a network of premium manufacturing partners. The goodwill related to the acquisition is not deductible for tax purposes. 

The Company recorded a contingent consideration liability of $13.6 million as of the acquisition date representing the estimated fair value of the amounts payable to former shareholders, as outlined under the terms of the merger agreement, payable subject to the satisfaction of performance-based targets during fiscal year 2021 and fiscal year 2022, consisting of up to $25.0 million in cash and up to 143,983 shares of the Company's common stock valued at $27.8 million on the date of close. The fair value of the contingent consideration (Level 3) is determined using a Monte Carlo pricing model. During the three and nine months ended September 30, 2021, the Company recorded a $0.8 million and $8.5 million decrease, respectively, to the estimated fair value of the contingent consideration liability, which was included as a decrease in general and administrative expense in the Consolidated Statements of Comprehensive Income. Fluctuations due to foreign currency translation have been recorded in the Consolidated Statements of Shareholders’ Equity.

The results of Hubs since the date of acquisition have been included with Protolabs' results. Pro forma disclosures of the consolidated results of the Company with the full year effects of Hubs, as if the acquisition had occurred on January 1, 2020, are not required and have not been separately presented since the impact to the Company's results of operations was not material.

The acquisition has been accounted for under the acquisition method of accounting in accordance with ASC 805, Business Combinations. In the second quarter of 2021, the Company recorded adjustments to the preliminary allocation, including a $3.9 million decrease to intangible assets, a $6.4 million increase to goodwill, a $3.3 million increase to contingent consideration, a $0.5 million decrease to deferred tax liabilities, and a decrease to cash paid of $0.3 million. The adjustments were driven by changes to the preliminary valuation and finalization of the working capital calculation. No adjustments were made in the third quarter of 2021. As of September 30, 2021, the allocation of purchase price to assets and liabilities is preliminary. The purchase price allocation will be finalized in 2021. The preliminary allocation is as follows:

Note 5 – Goodwill and Other Intangible Assets

The changes in the carrying amount of goodwill during the nine months ended September 30, 2021 were as follows:

Goodwill increased $281.8 million during the nine months ended September 30, 2021 as a result of our acquisition of Hubs. Goodwill has been allocated to the acquired Hubs entities consisting of goodwill of €106.5 million in Europe and $152.2 million in the United States as of the date of the acquisition. The Euro denominated goodwill is translated at the end of each period using the current exchange rates resulting in a foreign currency translation adjustment that is recorded as a component of Other Comprehensive Income.

Intangible assets other than goodwill at  September 30, 2021 and December 31, 2020 were as follows:

Intangible assets increased $30.8 million during the nine months ended September 30, 2021 as a result of our acquisition of Hubs. Intangible assets have been allocated to the acquired Hubs entities consisting of intangible assets of €11.6 million in Europe and $16.6 million in the United States as of the date of the acquisition. The Euro denominated intangible assets are translated at the end of each period using the current exchange rates resulting in a foreign currency translation adjustment that is recorded as a component of Other Comprehensive Income. Foreign currency losses related to intangible assets were $0.7 million as of September 30, 2021. There was no foreign currency translation impact as of December 31, 2020. Amortization expense for intangible assets was $1.6 million and $0.8 million for the three months ended  September 30, 2021 and 2020, respectively, and $4.6 million and $2.3 million for the nine months ended September 30, 2021 and 2020, respectively.

Estimated aggregated amortization expense based on the current carrying value of the amortizable intangible assets and current exchange rates is as follows:

Note 6 – Fair Value Measurements

Accounting Standards Codification, Fair Value Measurement (ASC 820), defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 also establishes a fair value hierarchy that requires classification based on observable and unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value:

Level 1—Quoted prices in active markets for identical assets or liabilities.

Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The Company's assets and liabilities that are required to be measured or disclosed at fair value on a recurring basis include cash and cash equivalents, marketable securities and contingent consideration. The Company’s cash consists of bank deposits. The Company’s cash equivalents measured at fair value consist of money market mutual funds. The Company determines the fair value of these investments using Level 1 inputs. The Company's marketable securities consist of short-term and long-term agency, municipal, corporate and other debt securities. Fair value for the corporate debt securities is primarily determined based on quoted market prices (Level 1). Fair values for the U.S. municipal securities, U.S. government agency securities, certificates of deposit and U.S. treasury securities are primarily determined using dealer quotes or quoted market prices for similar securities (Level 2). The Company's contingent consideration is the current fair value estimate of amounts owed to the former shareholders of Hubs and is determined using the Monte Carlo pricing model (Level 3).

The following table summarizes financial assets as of  September 30, 2021 and December 31, 2020 measured at fair value on a recurring basis: 

In the first quarter of 2021, the Company sold held-to-maturity securities in order to partially fund the acquisition of Hubs. As a result of the sale, all remaining marketable securities were reclassified to available-for-sale securities and reported at fair value.

The Company recorded a contingent consideration liability at the acquisition date of Hubs representing the amounts payable to former shareholders, as outlined under the terms of the merger agreement, payable subject to the satisfaction of performance-based targets during fiscal year 2021 and fiscal year 2022, consisting of up to $25.0 million in cash and up to 143,983 shares of the Company's common stock valued at $27.8 million on the date of close. The fair value of the contingent consideration (Level 3) is determined using a Monte Carlo pricing model. Subsequent changes in the fair value of the contingent consideration liabilities have been recorded in the Consolidated Statements of Comprehensive Income. Fluctuations due to foreign currency translation have been recorded in the Consolidated Statements of Shareholders’ Equity.

Note 7 – Marketable Securities

The Company invests in short-term and long-term agency, municipal, corporate and other debt securities. As of September 30, 2021, the securities are categorized as available-for-sale and are recorded at fair value. As of December 31, 2020, the securities were categorized as held-to-maturity and were recorded at amortized cost, net of an allowance for credit losses. The change in categorization was a result of the sale of securities in the first quarter of 2021 in order to partially fund the acquisition of Hubs and did not have a material impact on our financial statements. The following table summarizes information regarding the Company’s short-term and long-term marketable securities as of  September 30, 2021 and December 31, 2020:

Fair values for the corporate debt securities are primarily determined based on quoted market prices (Level 1). Fair values for the U.S. municipal securities, U.S. government agency securities, certificates of deposit and U.S. treasury securities are primarily determined using dealer quotes or quoted market prices for similar securities (Level 2).

During the first quarter of 2020, the Company adopted the FASB ASU 2016-13, Financial Instruments – Credit Losses. The Company calculated the expected credit loss for each security in its portfolio using the probability-of-default method. The Company concluded the adoption of the guidance had no material impact on its consolidated financial statements. 

Classification of marketable securities as current or non-current is based upon the security’s maturity date as of the date of these financial statements.

The  September 30, 2021 balance of available-for-sale debt securities by contractual maturity is shown in the following table at fair value. Actual maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties.

Note 8 – Inventory

Inventory consists primarily of raw materials, which are recorded at the lower of cost or market using the standard cost method, which approximates first-in, first-out (FIFO) cost. The Company periodically reviews its inventory for slow-moving, damaged and discontinued items and provides allowances to reduce such items identified to their recoverable amounts.

The Company’s inventory consisted of the following as of the dates indicated:

Note 9 – Stock-Based Compensation

Under the Company’s 2012 Long-Term Incentive Plan, as amended (the 2012 Plan), the Company has the ability to grant stock options, stock appreciation rights (SARs), restricted stock, restricted stock units, other stock-based awards and cash incentive awards. Awards under the 2012 Plan have a maximum term of ten years from the date of grant. The compensation committee may provide that the vesting or payment of any award will be subject to the attainment of specified performance measures in addition to the satisfaction of any continued service requirements and the compensation committee will determine whether such measures have been achieved. The per-share exercise price of stock options and SARs granted under the 2012 Plan generally may not be less than the fair market value of a share of our common stock on the date of the grant.

Employee Stock Purchase Plan

The Company’s 2012 Employee Stock Purchase Plan (ESPP) allows eligible employees to purchase a variable number of shares of the Company’s common stock each offering period at a discount through payroll deductions of up to 15 percent of their eligible compensation, subject to plan limitations. The ESPP provides for six-month offering periods with a single purchase period ending May 15 and November 15, respectively. At the end of each offering period, employees are able to purchase shares at 85 percent of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period.

Stock-Based Compensation Expense

Stock-based compensation expense was $5.0 million and $3.9 million for the three months ended  September 30, 2021 and 2020, respectively, and $15.5 million and $10.6 million for the nine months ended September 30, 2021 and 2020, respectively.

Stock Options

The following table summarizes stock option activity during the nine months ended September 30, 2021:

The outstanding options generally have a term of ten years. For employees, options granted become exercisable ratably over the vesting period, which is generally a period of four to five years, beginning on the first anniversary of the grant date, subject to the employee’s continuing service to the Company. For the board of directors, options generally become exercisable in full on the first anniversary of the grant date.

The weighted-average grant date fair value of options that were granted during the nine months ended September 30, 2021 was $57.26.

The following table provides the assumptions used in the Black-Scholes pricing model valuation of options during the nine months ended September 30, 2021 and 2020:

As of September 30, 2021, there was $5.4 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.8 years.

Restricted Stock

Restricted stock awards are share-settled awards and restrictions lapse ratably over the vesting period, which is generally a period from three to five years, beginning on the first anniversary of the grant date, subject to the employee's continuing service to the Company. For the board of directors, restrictions generally lapse in full on the first anniversary of the grant date. 

The following table summarizes restricted stock activity during the nine months ended September 30, 2021:

As of September 30, 2021, there was $31.7 million of unrecognized compensation expense related to non-vested restricted stock, which is expected to be recognized over a weighted-average period of 2.6 years. 

Performance Stock

Performance stock units (PSUs) are expressed in terms of a target number of PSUs, with anywhere between 0 percent and 150 percent of that target number capable of being earned and vesting at the end of a three-year performance period depending on the Company’s performance in the final year of the performance period and the award recipient’s continued employment. The Company’s PSUs granted from 2017 to 2019 and certain PSUs granted in 2021 are based on performance conditions and the related compensation cost is based on the probability that the performance conditions will be achieved. The Company’s PSUs granted in 2020 and certain PSUs granted in 2021 are based on market conditions and the related compensation cost is based on the fair value at grant date calculated using a Monte Carlo pricing model.

The following table summarizes performance stock activity during the nine months ended September 30, 2021:

The following table provides the assumptions used in the Monte Carlo pricing model valuation of PSUs during the nine months ended September 30, 2021 and 2020: 

As of September 30, 2021, there was $2.0 million of unrecognized compensation expense related to non-vested performance stock, which is expected to be recognized over a weighted-average period of 2.0 years. 

Employee Stock Purchase Plan

The following table presents the assumptions used to estimate the fair value of the ESPP during the nine months ended September 30, 2021 and 2020: 

 Note 10 – Accumulated Other Comprehensive Income (Loss)

Other comprehensive income (loss) is comprised of foreign currency translation adjustments and net unrealized gains (losses) on investments in securities. The following table presents the changes in accumulated other comprehensive income (loss) balances during the three and nine months ended September 30, 2021 and 2020:

Note 11 – Income Taxes

The Company is subject to income tax in multiple jurisdictions and the use of estimates is required to determine the provision for income taxes. For the three months ended  September 30, 2021 and 2020, the Company recorded an income tax provision of $2.2 million and $3.7 million, respectively. For the nine months ended  September 30, 2021 and 2020, the Company recorded an income tax provision of $5.8 million and $10.1 million, respectively. The income tax provision is based on the estimated annual effective tax rate for the year applied to pre-tax income. The effective income tax rate for the three months ended  September 30, 2021 was 31.5 percent compared to 20.1 percent in the same period of the prior year. The effective tax rate increased by 11.4 percent for the three months ended  September 30, 2021 when compared to the same period in 2020, primarily due to an increase in losses in jurisdictions that are not eligible for tax benefits due to valuation allowances. The effective income tax rate for the nine months ended  September 30, 2021 was 21.2 percent compared to 19.7 percent in the same period of the prior year. The effective tax rate increased by 1.5 percent for the nine months ended  September 30, 2021 when compared to the same period in 2020, primarily due to an increase in losses in jurisdictions that are not eligible for tax benefits due to valuation allowances.

The effective income tax rate for the nine months ended September 30, 2021 differs from the U.S. federal statutory rate of 21.0 percent due to various factors, including operating in multiple state and foreign jurisdictions and tax credits for which the Company qualifies.

The Company had unrecognized tax benefits totaling $5.0 million as of September 30, 2021 and $4.8 million as of  December 31, 2020, respectively, all of which, if recognized, would affect the Company’s effective tax rate. The Company recognizes interest and penalties related to income tax matters in income tax expense, and reports the liability in current or long-term income taxes payable as appropriate.

On March 11, 2021, the President signed into law the ARP Act, a legislative package which is generally not significant to the Company's current tax footprint; however, the Company will continue to assess the ARP Act on an ongoing basis. Similar tax provisions and other stimulus measures have been granted either before or after June 30, 2021 by certain foreign and U.S. state jurisdictions, which the Company continues to evaluate and apply, if applicable.

Note 12 – Segment Reporting

The Company’s reportable segments are based on the internal reporting used by the Company’s Chief Executive Officer, who is the chief operating decision maker (CODM), to assess operating performance and make decisions about the allocation of resources. The Corporate Unallocated and Japan category includes non-reportable segments, as well as research and development and general and administrative costs that the Company does not allocate directly to its operating segments.

Intercompany transactions primarily relate to intercontinental activity and have been eliminated and are excluded from the reported amounts. The difference between income from operations and pre-tax income relates to foreign currency-related gains and losses and interest income on cash balances and investments, which are not allocated to business segments. 

Revenue and income from operations by reportable segment for the three and nine months ended September 30, 2021 and 2020 were as follows:

Total long-lived assets at  September 30, 2021 and December 31, 2020 were as follows:

Revenue by product line for the three and nine months ended September 30, 2021 and 2020 were as follows:

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

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our unaudited consolidated financial statements and related notes appearing elsewhere in this Quarterly Report on Form 10-Q and our Annual Report on Form 10-K for the year ended December 31, 2020.

Forward-Looking Statements

Statements contained in this report regarding matters that are not historical or current facts are “forward-looking statements” within the meaning of The Private Securities Litigation Reform Act of 1995. In some cases, you can identify forward-looking statements by the following words: “may,” “will,” “could,” “would,” “should,” “expect,” “intend,” “plan,” “anticipate,” “believe,” “estimate,” “predict,” “project,” “potential,” “continue,” “ongoing” or the negative of these terms or other comparable terminology, although not all forward-looking statements contain these words. These statements involve known and unknown risks, uncertainties and other factors that may cause our results to be materially different than those expressed or implied in such statements. Certain of these risk factors and others are described in Item 1A. “Risk Factors” of this Form 10-Q, as well as our most recent Annual Report on Form 10-K as filed with the Securities and Exchange Commission (SEC). Other unknown or unpredictable factors also could have material adverse effects on our future results. We cannot guarantee future results, levels of activity, performance or achievements. Accordingly, you should not place undue reliance on these forward-looking statements. Finally, we expressly disclaim any intent or obligation to update any forward-looking statements to reflect subsequent events or circumstances.

Overview

We are the world’s largest and fastest digital manufacturer of custom prototypes and on-demand production parts. We manufacture prototypes and low-volume production parts for companies worldwide that are under increasing pressure to bring their finished products to market faster than their competition. We utilize injection molding, computer numerical control (CNC) machining, 3D printing and sheet metal fabrication to manufacture custom parts for our customers. Our proprietary technology eliminates most of the time-consuming and expensive skilled labor conventionally required to quote and manufacture parts. In January 2021, we acquired Hubs, a leading online manufacturing platform based in Amsterdam, Netherlands, that provides customers with on-demand access to a global network of premium manufacturing partners. This acquisition creates the world's most comprehensive digital manufacturing offer, offering the broadest set of manufacturing services with the help of a global network of premium manufacturing providers. Our customers conduct nearly all of their business with us over the Internet. We target our products at the millions of product developers and engineers who use three-dimensional computer-aided design (3D CAD) software to design products across a diverse range of end-markets.

Our primary manufacturing product lines currently include Injection Molding, CNC Machining, 3D Printing and Sheet Metal. We continually seek to expand the range of sizes and geometric complexity of the parts we can make with these processes, to extend the variety of materials we are able to support, and to identify additional manufacturing processes to which we can apply our technology in order to better serve the evolving preferences and needs of product developers and engineers. The acquisition of Hubs broadens our offer beyond our current manufacturing capabilities and provides a broader range of price and lead time options by leveraging a network of manufacturing partners to meet the holistic needs of our customers.

Injection Molding

Our Injection Molding product line uses our 3D CAD-to-CNC machining technology for the automated design and manufacture of molds, which are then used to produce custom plastic and liquid silicone rubber injection-molded parts and over-molded and insert-molded injection-molded parts on commercially available equipment. Our Injection Molding product line works best for on-demand production, bridge tooling, pilot runs and functional prototyping. Our affordable aluminum molds and quick turnaround times help reduce design risk and limit overall production costs for product developers and engineers. In 2017, we launched an on-demand manufacturing injection molding product offering. Customers who need short-run production often come back to Protolabs’ Injection Molding product line for additional quantities. They do so to support pilot production for product testing, while their tooling for high-volume production is being prepared, because they need on-demand manufacturing due to disruptions in their manufacturing process, because their product requires limited annual quantity or because they need end-of-life production support.

CNC Machining

Our CNC Machining product line uses commercially available CNC machines to manufacture custom metal and plastic parts through processes such as CNC milling and CNC turning. CNC milling is a manufacturing process that cuts plastic and metal blocks into one or more custom parts based on the 3D CAD model uploaded by the customer. CNC turning with live tooling combines both lathe and mill capabilities to machine parts with cylindrical features from metal rod stock. Our efficiencies derive from the automation of the programming of these machines and a proprietary fixturing process.

Quick-turn CNC machining works best for prototyping, form and fit testing, jigs and fixtures and functional components for end-use applications.

3D Printing

Our 3D Printing product line includes a broad range of technologies in plastics and metals, stereolithography, selective laser sintering, direct metal laser sintering, Multi Jet Fusion, PolyJet and digital light synthesis processes, which offer customers a wide-variety of high-quality, precision rapid prototyping and low-volume production. These processes create parts with a high level of accuracy, detail, strength and durability. Industrial 3D Printing is best suited for functional prototypes, complex designs and end-use applications.

Sheet Metal

Our Sheet Metal product line includes quick-turn and e-commerce-enabled custom sheet metal parts and assemblies, which provide customers with prototype and low-volume production parts. The rapid prototype sheet metal process is most often used when form, fit and function are all a priority. Our manufacturing process uses customer 3D CAD models uploaded by the product developer or engineer to fabricate quick-turn prototype sheet metal or short-run production parts.

Key Financial Measures and Trends

Revenue

Our operations are comprised of three geographic operating segments in the United States, Europe and Japan. Revenue is derived from our Injection Molding, CNC Machining, 3D Printing and Sheet Metal product lines. Injection Molding revenue consists of sales of custom injection molds and injection-molded parts. CNC Machining revenue consists of sales of CNC-machined custom parts. 3D Printing revenue consists of sales of 3D-printed parts. Sheet Metal revenue consists of sales of fabricated sheet metal custom parts. Our historical and current efforts to increase revenue have been directed at expanding the breadth of our product offerings, gaining new customers and selling to our existing customer base by increasing marketing and selling activities, including:

During the three months ended September 30, 2021, we served 23,457 unique product developers and engineers who purchased our products through our web-based customer interface, an increase of 24.8% over the same period in 2020. The increase in product developers was driven primarily by our acquisition of Hubs. Excluding the impact of Hubs, our product developers increased 7.3% during the three months ended September 30, 2021 when compared to the same period in 2020. During the nine months ended September 30, 2021, we served 49,300 unique product developers and engineers who purchased our products through our web-based customer interface, an increase of 31.5% over the same period in 2020. The increase in unique product developers served was driven primarily by our acquisition of Hubs. Excluding the impact of Hubs, unique product developers served increased 10.7% during the nine months ended September 30, 2021 when compared to the same period in 2020.

Cost of Revenue, Gross Profit and Gross Margin

Cost of revenue consists primarily of raw materials, equipment depreciation, employee compensation, benefits, stock-based compensation, facilities costs, overhead allocations and outsourced manufacturing costs associated with the manufacturing process for molds and custom parts. We expect our personnel-related costs to increase in order to retain and attract top talent and remain competitive in the market. Overall, we expect cost of revenue to increase in absolute dollars.

We define gross profit as our revenue less our cost of revenue, and we define gross margin as gross profit expressed as a percentage of revenue. We expect our gross profit to increase in absolute dollars, however our gross margin may fluctuate based on the business mix in each reporting period. Our gross profit and gross margin are affected by many factors, including our mix of revenue by product line, pricing, sales volume, manufacturing costs, the costs associated with increasing production capacity, the mix between domestic and foreign revenue sources, the mix between revenue produced in our internal manufacturing operations and outsourced to our external manufacturing partners and foreign exchange rates.

Operating Expenses

Operating expenses consist of marketing and sales, research and development and general and administrative expenses. Personnel-related costs are the most significant component in each of these categories.

Our recent growth in operating expenses is mainly due to the launch of our Protolabs 2.0 project, an internal business systems project impacting both external customer-facing and internal back-end systems, in the fourth quarter of 2020. During the development of Protolabs 2.0, certain research and development personnel costs were capitalizable as a software development asset. Since the system was placed in service in November 2020, the personnel costs have been expensed as incurred. In addition, amortization expense for the software asset is now being recorded over the systems’ estimated useful lives of seven to 10 years. Our business strategy is to continue to be a leading online and technology-enabled manufacturer of quick-turn, on-demand injection-molded, CNC-machined, 3D-printed and sheet metal custom parts for prototyping and low-volume production. In order to achieve our goals, we anticipate continued substantial investments in technology and personnel, resulting in increased operating expenses.

Marketing and sales. Marketing and sales expense consists primarily of employee compensation, benefits, commissions, stock-based compensation, marketing programs such as electronic, print and pay-per-click advertising, trade shows and other related overhead, which includes an allocation of information technology expense including amortization of Protolabs 2.0 software assets. We expect sales and marketing expense to increase in the future as we increase the number of marketing and sales professionals and marketing programs targeted to increase our customer base and grow revenue.

Research and development. Research and development expense consists primarily of personnel and outside service costs related to the development of new processes and product lines, enhancement of existing product lines, development of software for internal use, maintenance of internally developed software, quality assurance and testing. Costs for internal use software are evaluated by project and capitalized where appropriate under ASC 350-40, Intangibles — Goodwill and Other, Internal-Use Software. We expect research and development expense to increase in the future as we seek to enhance our e-commerce interface technology, internal software and supporting business systems, and continue to expand our product lines.

General and administrative. General and administrative expense consists primarily of employee compensation, benefits, stock-based compensation, professional service fees related to accounting, tax and legal, and other related overhead, which includes an allocation of information technology expense including amortization of Protolabs 2.0 software assets. We expect general and administrative expense to increase in the future as we continue to grow and expand as a global organization.

Other Income, net

Other income, net primarily consists of foreign currency-related gains and losses and interest income on cash balances and investments. Our foreign currency-related gains and losses will vary depending upon movements in underlying exchange rates. Our interest income will vary each reporting period depending on our average cash balances during the period, composition of our marketable security portfolio and the current level of interest rates.

Provision for Income Taxes

Provision for income taxes is comprised of federal, state, local and foreign taxes based on pre-tax income. Overall, we expect our effective tax rate for 2021 and beyond will remain consistent based on the current tax laws.

Results of Operations

The following table summarizes our results of operations and the related changes for the periods indicated. The results below are not necessarily indicative of the results for future periods.