Biggest changeYear Ended December 31, 2023 2022 2021 Consolidated Statements of Operations: Revenue $ 267,014 $ 256,380 $ 226,908 Cost of revenue (1) 99,229 81,512 58,313 Gross profit 167,785 174,868 168,595 Operating expenses (1) : Technology and development 26,727 20,846 15,885 Sales and marketing 82,803 68,562 58,160 General and administrative 56,219 44,940 35,761 Total operating expenses 165,749 134,348 109,806 Operating income 2,036 40,520 58,789 Total other income (expense), net 8,469 (3,053) 6,014 Income before income taxes 10,505 37,467 64,803 Provision for income taxes 1,624 8,762 8,199 Net income $ 8,881 $ 28,705 $ 56,604 _______________ (1) Amounts include stock-based compensation expense before tax benefit as follows: Year Ended December 31, 2023 2022 2021 (in thousands) Cost of revenue $ 1,472 $ 1,135 $ 825 Technology and development 4,346 3,225 2,232 Sales and marketing 10,462 7,645 5,176 General and administrative 12,582 8,641 5,874 Total stock-based compensation expense $ 28,862 $ 20,646 $ 14,107 Year Ended December 31, 2023 2022 2021 (as percentage of revenue) Revenue 100 % 100 % 100 % Cost of revenue 37 32 26 Gross profit 63 68 74 Operating expenses: Technology and development 10 8 7 Sales and marketing 31 27 26 General and administrative 21 17 16 Total operating expenses 62 52 49 Operating income 1 16 25 Total other income (expense), net 3 (2) 4 Income before income taxes 4 14 29 Provision for income taxes 1 3 4 Net income 3 % 11 % 25 % 49 Table of Contents Comparison of the Years Ended December 31, 2023 and 2022 Revenue, Cost of Revenue and Gross Profit Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) Revenue $ 267,014 $ 256,380 $ 10,634 4 % Cost of revenue 99,229 81,512 17,717 22 % Gross profit $ 167,785 $ 174,868 $ (7,083) (4) % Gross profit margin 63 % 68 % Revenue increased $10.6 million, or 4%, in 2023 driven by growth in impressions processed on our platform from both existing and new publishers.
Biggest changeYear Ended December 31, 2024 2023 2022 Consolidated Statements of Operations: Revenue $ 291,256 $ 267,014 $ 256,380 Cost of revenue (1) 101,027 99,229 81,512 Gross profit 190,229 167,785 174,868 Operating expenses (1) : Technology and development 33,263 26,727 20,846 Sales and marketing 95,369 82,803 68,562 General and administrative 57,670 56,219 44,940 Total operating expenses 186,302 165,749 134,348 Operating income 3,927 2,036 40,520 Total other income (expense), net 13,847 8,469 (3,053) Income before income taxes 17,774 10,505 37,467 Provision for income taxes 5,270 1,624 8,762 Net income $ 12,504 $ 8,881 $ 28,705 _______________ (1) Amounts include stock-based compensation expense before tax benefit as follows: Year Ended December 31, 2024 2023 2022 (in thousands) Cost of revenue $ 1,855 $ 1,472 $ 1,135 Technology and development 6,313 4,346 3,225 Sales and marketing 13,407 10,462 7,645 General and administrative 16,101 12,582 8,641 Total stock-based compensation expense $ 37,676 $ 28,862 $ 20,646 Year Ended December 31, 2024 2023 2022 (as percentage of revenue) Revenue 100 % 100 % 100 % Cost of revenue 35 37 32 Gross profit 65 63 68 Operating expenses: Technology and development 11 10 8 Sales and marketing 33 31 27 General and administrative 20 21 17 Total operating expenses 64 62 52 Operating income 1 1 16 Total other income (expense), net 5 3 (2) Income before income taxes 6 4 14 Provision for income taxes 2 1 3 Net income 4 % 3 % 11 % 49 Table of Contents Comparison of the Years Ended December 31, 2024 and 2023 Revenue, Cost of Revenue and Gross Profit Year Ended December 31, 2024 2023 $ Change % Change (dollars in thousands) Revenue $ 291,256 $ 267,014 $ 24,242 9 % Cost of revenue 101,027 99,229 1,798 2 % Gross profit $ 190,229 $ 167,785 $ 22,444 13 % Gross profit margin 65 % 63 % Revenue increased $24.2 million, or 9%, in 2024 primarily due to an increase in the number of ad impressions processed from our publishers, growth in our emerging revenue streams, and increased demand from the growth of our buyer relationships primarily through SPO agreements.
Financing Activities For the year ended December 31, 2023, net cash used in financing activities of $56.0 million was primarily due to $59.3 million in stock repurchases, offset by $1.5 million proceeds from stock option exercises and $1.9 million proceeds from the employee stock purchase plan.
For the year ended December 31, 2023, net cash used in financing activities of $56.0 million was primarily due to $59.3 million in stock repurchases, offset by $1.5 million in proceeds from stock option exercises and $1.9 million in proceeds from the employee stock purchase plan.
Valuable ad impressions are transparent and data rich, viewable by humans, and verifiable. Each ad impression we auction consists of 573 independent data parameters, which can yield valuable insights if recorded and analyzed properly. This processing of voluminous data for each ad impression must occur in less than half a second as consumers expect a seamless digital ad experience.
Valuable ad impressions are transparent and data rich, viewable by humans, and verifiable. Each ad impression we auction consists of 644 independent data parameters, which can yield valuable insights if recorded and analyzed properly. This processing of voluminous data for each ad impression must occur in less than half a second as consumers expect a seamless digital ad experience.
Most notably, advertisers have historically spent relatively more in the fourth quarter of the calendar year to coincide with the holiday shopping season, and relatively less in the first quarter.
Most notably, advertisers have historically spent more in the fourth quarter of the calendar year to coincide with the holiday shopping season, and less in the first quarter.
Personnel costs include salaries, bonuses, stock-based compensation, and employee benefit costs, and are primarily attributable to our cloud operations group, which maintains our servers, and our client operations group, which is responsible for the integration of new publishers and buyers and providing customer support for existing customers. Operating Expenses Technology and Development.
Personnel costs include salaries, bonuses, stock-based compensation, and employee benefit costs, and are primarily attributable to our network operations group, which maintains our servers, and our client operations group, which is responsible for the integration of new publishers and buyers and providing customer support for existing customers. Operating Expenses Technology and Development.
For purposes of our publisher count, we aggregate multiple business accounts from separate divisions, segments or subsidiaries into a single “master” publisher based on our assessment of the related nature of the group. In addition, in 2023 we completed a number of SPO initiatives which increased buyer spend on our platform.
For purposes of our publisher count, we aggregate multiple business accounts from separate divisions, segments or subsidiaries into a single “master” publisher based on our assessment of the related nature of the group. In addition, in 2024 we completed a number of SPO initiatives which increased buyer spend on our platform.
We expect the cost of revenue to be higher in 2024 compared to 2023 in absolute dollars primarily due to increases in depreciation and amortization expense from data center capacity expansion in 2023, as well as increases in in software, hardware and equipment maintenance to support the data centers.
We expect the cost of revenue to be higher in 2025 compared to 2024 in absolute dollars primarily due to increases in depreciation and amortization expense from data center capacity expansion in 2024, as well as increases in in software, hardware and equipment maintenance to support the data centers.
For discussion on comparison of the fiscal years ended December 31, 2022 and December 31, 2021, please refer to Part II, Item 7, “Management's Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022.
For discussion on comparison of the fiscal years ended December 31, 2023 and December 31, 2022, please refer to Part II, Item 7, “Management's Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2023.
Our revenue recognition policies are discussed in more detail under “Critical Accounting Policies and Estimates.” 47 Table of Contents Cost of Revenue Cost of revenue consists of data center co-location costs, depreciation expense related to hardware supporting our platform, amortization expense related to capitalized internal use software development costs, personnel costs, and allocated facilities costs.
Our revenue recognition policies are discussed in more detail under “Critical Accounting Policies and Estimates.” 47 Table of Contents Cost of Revenue Cost of revenue consists of data center co-location costs, depreciation expense related to hardware supporting our platform, amortization expense related to capitalized internal use software development costs and acquired developed technology, personnel costs, and allocated facilities costs.
Therefore, we consider these to be our critical accounting policies and estimates. 55 Table of Contents Revenue Recognition We refer to our publishers, app developers, and channel partners collectively as our publishers. We generate revenue through the monetization of publisher ad impressions processed on our platform.
Therefore, we consider these to be our critical accounting policies and estimates. Revenue Recognition We refer to our publishers, app developers, and channel partners collectively as our publishers. We generate revenue through the monetization of publisher ad impressions processed on our platform.
We have been investing in SPO technology and partnerships for five years and SPO represented approximately 45% of total activity for the year ended December 31, 2023. 46 Table of Contents Monetization Excellence We focus on monetizing digital impressions by coordinating over a hundred billion real-time auctions and nearly a trillion bids globally on a daily basis, using our specialized cloud software, machine learning algorithms, and scaled transaction infrastructure.
We have been investing in SPO technology and partnerships for six years and SPO represented approximately 50% of total activity for the year ended December 31, 2024. 46 Table of Contents Monetization Excellence We focus on monetizing digital impressions by coordinating over a hundred billion real-time auctions and nearly a trillion bids globally on a daily basis, using our specialized cloud software, machine learning algorithms, and scaled transaction infrastructure.
We expect sales and marketing expenses to increase in 2024 compared to 2023 in absolute dollars primarily due to additional headcount investment and marketing programs.
We expect sales and marketing expenses to increase in 2025 compared to 2024 in absolute dollars primarily due to additional headcount investment and marketing programs.
We expect general and administrative expenses to increase in 2024 compared to 2023 in absolute dollars primarily due to increases in expenses relating to our personnel.
We expect general and administrative expenses to increase in 2025 compared to 2024 in absolute dollars primarily due to increases in expenses relating to our personnel.
For discussion on operating, investing, and financing activities of the fiscal year ended December 31, 2021, see the Liquidity and Capital Resources section disclosed in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of our Annual Report on Form 10-K, which was filed with the SEC on March 1, 2022 and hereby incorporated by reference herein and considered part of this Annual Report on Form 10-K only to the extent referenced.
For discussion on operating, investing, and financing activities of the fiscal year ended December 31, 2022, see the Liquidity and Capital Resources section disclosed in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of our Annual Report on Form 10-K, which was filed with the SEC on February 28, 2023 and hereby incorporated by reference herein and considered part of this Annual Report on Form 10-K only to the extent referenced.
For the year ended December 31, 2023, we used $39.0 million of cash in investing activities, consisting of a net increase in investments of marketable securities of $29.6 million, $10.6 million in purchases of property and equipment (primarily data center infrastructure), $17.7 million of investments in capitalized internal use software, offset by an increase from sales of marketable securities prior to maturity of $18.9 million.
For the year ended December 31, 2023, net cash used in investing activities was $39.0 million, consisting of a net purchase of investments of marketable securities of $29.6 million, $10.6 million in purchases of property and equipment (primarily data center infrastructure), $17.7 million of investments in capitalized internal use software, offset by net inflows from sales of marketable securities prior to maturity of $18.9 million.
Additionally, recent interest rate increases, foreign currency fluctuation and persistent inflation in the U.S. and other markets globally continue to create economic volatility and dislocation in the capital and credit markets in the U.S. and globally.
Additionally, recent foreign currency fluctuation and persistent inflation in the U.S. and other markets globally continue to create economic volatility and dislocation in the capital and credit markets in the U.S. and globally.
As of December 31, 2023, the applicable interest rate under the Revolving Credit Facility was 9.50%. We had no amounts outstanding under the Revolving Credit Facility as of December 31, 2023. The Credit Agreement contains customary representations and warranties as well as customary affirmative and negative covenants.
As of December 31, 2024, the applicable interest rate under the Revolving Credit Facility was 8.50%. We had no amounts outstanding under the Revolving Credit Facility as of December 31, 2024. The Credit Agreement contains customary representations and warranties as well as customary affirmative and negative covenants.
The difference between the effective tax rate in 2022 of 23% and the federal statutory income tax rate of 21% was primarily due to state taxes, stock-based compensation, and Section 162(m) limitation partially offset by federal research and development credit, and a foreign derived intangible income deduction.
The difference between the effective tax rate in 2023 of 15% and the federal statutory income tax rate of 21% was primarily due to federal research and development credit and foreign derived intangible income (FDII) deduction partially offset by state taxes, stock-based compensation, and Section 162(m) limitation.
Cash flows from operating activities have been affected by changes in our working capital, particularly changes in accounts receivable and accounts payable. The timing of cash receipts from buyers and payments to publishers can significantly impact our cash flows from operating activities. In addition, we expect seasonality to impact quarterly cash flows from operating activities.
Cash flows from operating activities have been affected by changes in our working capital, particularly changes in accounts receivable and accounts payable. The timing of cash receipts from buyers and payments to publishers can significantly impact our cash flows from operating activities.
Because of these and other limitations, you should consider Adjusted EBITDA along with other GAAP-based financial performance measures, including net income and our GAAP financial results. Liquidity and Capital Resources We have financed our operations and capital expenditures primarily through utilization of cash generated from operations, as well as a public offering of our common stock.
Because of these and other limitations, you should consider Adjusted EBITDA along with other GAAP-based financial performance measures, including net income and our GAAP financial results. Liquidity and Capital Resources We have financed our operations and capital expenditures primarily through utilization of cash generated from operations.
For the year ended 2023, we served approximately 1,800 publishers worldwide on our platform, compared to approximately 1,650 publishers worldwide for the year ended 2022.
For the year ended 2024, we served approximately 1,900 publishers worldwide on our platform, compared to approximately 1,800 publishers worldwide for the year ended 2023.
The following table presents a reconciliation of Adjusted EBITDA to net income for each of the periods indicated: Year Ended December 31, 2023 2022 2021 (in thousands) Net income $ 8,881 $ 28,705 $ 56,604 Add back (deduct): Stock-based compensation 28,862 20,646 14,107 Depreciation and amortization 44,770 34,249 23,073 Unrealized (gain), loss and impairment of equity investment — 5,948 (5,433) Interest income (8,828) (2,214) (300) Acquisition-related and other expenses (1) — 918 — Provision for income taxes 1,624 8,762 8,199 Adjusted EBITDA $ 75,309 $ 97,014 $ 96,250 _______________ (1) We exclude acquisition-related and other expenses incurred in connection with our acquisition of Martin from Adjusted EBITDA because we do not believe such expenses are reflective of our ongoing core operations.
The following table presents a reconciliation of Adjusted EBITDA to net income for each of the periods indicated: Year Ended December 31, 2024 2023 2022 (in thousands) Net income $ 12,504 $ 8,881 $ 28,705 Add back (deduct): Stock-based compensation 37,676 28,862 20,646 Depreciation and amortization 45,352 44,770 34,249 Unrealized loss and impairment of equity investment — — 5,948 Interest income (8,477) (8,828) (2,214) Acquisition-related and other expenses (1) — — 918 Provision for income taxes 5,270 1,624 8,762 Adjusted EBITDA $ 92,325 $ 75,309 $ 97,014 _______________ (1) We exclude acquisition-related and other expenses incurred in connection with our acquisition of Martin from Adjusted EBITDA because we do not believe such expenses are reflective of our ongoing core operations.
See “Risk Factors” for further discussion of the risks related to inflation, rising interest rates, foreign currency fluctuations and public health crises on our business. 45 Table of Contents Financial Results Overview The table below summarizes the financial highlights of our business: Year Ended December 31, 2023 2022 2021 (in thousands) Revenue $ 267,014 $ 256,380 $ 226,908 Operating income 2,036 40,520 58,789 Net income 8,881 28,705 56,604 Adjusted EBITDA (1) 75,309 97,014 96,250 Net cash provided by operating activities 81,121 87,212 88,681 _______________ (1) For a definition of Adjusted EBITDA, an explanation of our management’s use of this measure, and a reconciliation of Adjusted EBITDA to net income, see “Non-GAAP Financial Measures” below.
See “Risk Factors” for further discussion of the risks related to inflation, volatile interest rates, foreign currency fluctuations and public health crises on our business. 45 Table of Contents Financial Results Overview The table below summarizes the financial highlights of our business: Year Ended December 31, 2024 2023 2022 (in thousands) Revenue $ 291,256 $ 267,014 $ 256,380 Operating income $ 3,927 $ 2,036 $ 40,520 Net income $ 12,504 $ 8,881 $ 28,705 Adjusted EBITDA (1) $ 92,325 $ 75,309 $ 97,014 Net cash provided by operating activities $ 73,425 $ 81,121 $ 87,212 _______________ (1) For a definition of Adjusted EBITDA, an explanation of our management’s use of this measure, and a reconciliation of Adjusted EBITDA to net income, see “Non-GAAP Financial Measures” below.
For additional information, see Note 7, “Business Combination” to our consolidated financial statements included elsewhere in this Annual Report on Form 10-K. In addition to operating income and net income, we use Adjusted EBITDA as a measure of operational efficiency.
Acquisition-related expenses incurred in connection with our acquisition of Martin include third-party transaction costs. For additional information, see Note 7, “Business Combination” to our consolidated financial statements included elsewhere in this Annual Report on Form 10-K. In addition to operating income and net income, we use Adjusted EBITDA as a measure of operational efficiency.
As a result, this amount is not included in the contractual obligations table above. Credit Facilities On October 17, 2022, we entered into a Senior Secured Credit Facilities Credit Agreement (the “Credit Agreement”) with the several lenders parties thereto, and Silicon Valley Bank, as administrative agent, lead arranger, issuing lender, and swingline lender.
Credit Facilities On October 17, 2022, we entered into a Senior Secured Credit Facilities Credit Agreement (the “Credit Agreement”) with the several lenders parties thereto, and Silicon Valley Bank, as administrative agent, lead arranger, issuing lender, and swingline lender.
We ended fiscal 2023 with approximately 150 net new publishers in 2023, which represented over 66,000 domains and 29,000 apps in total, compared to approximately 200 new publishers in 2022, which represented approximately 67,000 domains and 25,000 apps in total.
We ended fiscal 2024 with approximately 100 net new publishers, which represented over 60,000 domains and 27,000 apps in total, compared to approximately 150 new publishers in 2023, which represented approximately 66,000 domains and 29,000 apps in total.
Technology and Development Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) Technology and development $ 26,727 $ 20,846 $ 5,881 28 % Percent of revenue 10 % 8 % The increase in technology and development costs was primarily due to an increase of $11.1 million in personnel costs associated with a headcount increase by 11% and higher stock-based compensation costs, an increase of $1.0 million in facilities costs associated with new offices, offset by a $6.7 million increase in the capitalization of internal use software.
Technology and Development Year Ended December 31, 2024 2023 $ Change % Change (dollars in thousands) Technology and development $ 33,263 $ 26,727 $ 6,536 24 % Percent of revenue 11 % 10 % The increase in technology and development costs was primarily due to an increase of $7.5 million in personnel costs associated with a headcount increase by 13% and higher stock-based compensation costs, an increase of $0.7 million in facilities costs associated with new offices, an increase in depreciation of $0.3 million, and an increase in travel and entertainment of $0.3 million, offset by a $2.3 million increase in the capitalization of internal use software.
General and administrative expenses also include outside consulting, legal and accounting services, allocated facilities costs, and travel and entertainment primarily related to inter-office travel and conferences.
General and administrative expenses also include outside consulting, legal and accounting services, allocated facilities costs, and travel and entertainment primarily related to inter-office travel and conferences. We expect general and administrative expenses to increase in absolute dollars in future periods.
We expect technology and development expenses to increase in 2024 compared to 2023 in absolute dollars, primarily due to the additional headcount investment in our key growth opportunities. 50 Table of Contents Sales and Marketing Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) Sales and marketing $ 82,803 $ 68,562 $ 14,241 21 % Percent of revenue 31 % 27 % Sales and marketing costs increased primarily due to a $10.7 million increase in personnel costs associated with a headcount increase by 5% and higher stock-based compensation costs, a $2.2 million increase in travel and entertainment expenses, and a $0.7 million increase in amortization for acquisition-related intangible assets.
We expect technology and development expenses to increase in 2025 compared to 2024 in absolute dollars, primarily due to the additional headcount investment in our key growth opportunities. 50 Table of Contents Sales and Marketing Year Ended December 31, 2024 2023 $ Change % Change (dollars in thousands) Sales and marketing $ 95,369 $ 82,803 $ 12,566 15 % Percent of revenue 33 % 31 % Sales and marketing costs increased primarily due to a $11.7 million increase in personnel costs associated with a headcount increase by 7% and higher stock-based compensation costs and a $1.1 million increase in facilities costs, increase in travel and entertainment expenses of $0.4 million, and increase in marketing expenses of $0.2 million, offset by a decrease in amortization for acquisition-related intangible assets of $0.9 million.
The number of ad impressions processed on our platform was approximately 46.5 trillion, 48.8 trillion, 56.0 trillion, and 59.4 trillion for each of the three months ended March 31, 2023, June 30, 2023, September 30, 2023, and December 31, 2023, respectively, as compared to 32.6 trillion, 36.2 trillion, 42.1 trillion, and 48.2 trillion for each of the three months ended March 31, 2022, June 30, 2022, September 30, 2022, and December 31, 2022, respectively.
The number of ad impressions processed on our platform was approximately 57.9 trillion, 60.7 trillion, 69.8 trillion, and 74.7 trillion for each of the three months ended March 31, 2024, June 30, 2024, September 30, 2024, and December 31, 2024, respectively, as compared to 46.5 trillion, 48.8 trillion, 56.0 trillion, and 59.4 trillion for each of the three months ended March 31, 2023, June 30, 2023, September 30, 2023, and December 31, 2023, respectively.
The determination as to whether revenue should be reported gross of amounts billed to buyers (gross basis) or net of payments to publishers (net basis) requires significant judgment, and is based on our assessment of whether we are acting as the principal or an agent in the transaction.
We estimate and record reductions to revenue for volume discounts based on expected volumes during the incentive term. 55 Table of Contents The determination as to whether revenue should be reported gross of amounts billed to buyers (gross basis) or net of payments to publishers (net basis) requires significant judgment, and is based on our assessment of whether we are acting as the principal or an agent in the transaction.
Events or changes in circumstances which could trigger an impairment review include a significant adverse change in legal factors or in the business climate, an adverse action or assessment by a regulator, unanticipated competition, a loss of key personnel, significant changes in the manner of the Company’s use of the acquired assets, or the strategy for the Company’s overall business, significant negative industry or economic trends, or significant underperformance relative to expected historical or projected future results of operations.
Acquisition-related intangible assets and goodwill are tested for impairment at least annually or more frequently if events or changes in circumstances indicate that the acquisition-related intangible assets or goodwill may be impaired. 56 Table of Contents Events or changes in circumstances which could trigger an impairment review include a significant adverse change in legal factors or in the business climate, an adverse action or assessment by a regulator, unanticipated competition, a loss of key personnel, significant changes in the manner of the Company’s use of the acquired assets, or the strategy for the Company’s overall business, significant negative industry or economic trends, or significant underperformance relative to expected historical or projected future results of operations.
General and Administrative Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) General and administrative $ 56,219 $ 44,940 $ 11,279 25 % Percent of revenue 21 % 17 % General and administrative expense increased primarily due to a $6.4 million increase in personnel costs associated with higher stock-based compensation costs, and a $5.7 million increase in provision for bad debt relating to a DSP buyer of our platform that filed for Chapter 11 bankruptcy.
General and Administrative Year Ended December 31, 2024 2023 $ Change % Change (dollars in thousands) General and administrative $ 57,670 $ 56,219 $ 1,451 3 % Percent of revenue 20 % 21 % General and administrative expense increased primarily due to a $6.3 million increase in personnel costs associated with higher stock-based compensation costs, and a $1.1 million increase in professional services, offset by a $5.7 million decrease in provision for bad debt relating to a DSP buyer of our platform that filed for Chapter 11 bankruptcy on June 30, 2023.
Further, we work with DSPs to help them reduce their costs and improve advertiser ROI, which in turn makes us the specialized cloud infrastructure platform of choice for many of our buying partners.
Our net dollar-based retention rate was 107% for the year ended December 31, 2024, and 101% for the year ended December 31, 2023. Further, we work with DSPs to help them reduce their costs and improve advertiser ROI, which in turn makes us the specialized cloud infrastructure platform of choice for many of our buying partners.
Cost of revenue increased $17.7 million, primarily due to a $4.0 million increase in depreciation of data center equipment, a $3.8 million increase in amortization of internal use software, a $6.2 million increase in data centers expansion and upgrades, a $2.0 million increase in personnel costs as headcount increased by 12% in order to support our growing business, and a $1.1 million increase in amortization for acquisition-related intangible assets.
Cost of revenue increased $1.8 million, primarily due to a $5.1 million increase in amortization of internal use software and a $1.3 million increase in personnel costs as headcount increased by 4% in order to support our growing business, offset by a $3.8 million decrease in depreciation of data center equipment.
For the year ended December 31, 2022, net cash provided by financing activities of $4.0 million was primarily due to $1.2 million in proceeds from stock option exercises and $3.0 million in proceeds from the employee stock purchase plan.
Financing Activities For the year ended December 31, 2024, net cash used in financing activities of $73.5 million was primarily due to $75.3 million in stock repurchases and $2.1 million in payment of a business combination indemnification holdback, offset by $1.8 million proceeds from stock option exercises and $2.4 million proceeds from the employee stock purchase plan.
Cash Flows The following table summarizes our cash flows for the periods presented: Year Ended December 31, 2023 2022 2021 (in thousands) Net cash provided by operating activities $ 81,121 $ 87,212 $ 88,681 Net cash used in investing activities (39,018) (81,371) (96,723) Net cash provided by (used in) financing activities (55,976) 4,036 9,359 Net increase (decrease) in cash and cash equivalents $ (13,873) $ 9,877 $ 1,317 53 Table of Contents Operating Activities Our cash flows from operating activities are primarily influenced by growth in our operations, increases or decreases in collections from our buyers and related payments to our publishers, as well as our investment in personnel to support the anticipated growth of our business.
Our future capital requirements and the adequacy of available funds will depend on many factors, including those set forth under “Risk Factors.” Cash Flows The following table summarizes our cash flows for the periods presented: Year Ended December 31, 2024 2023 2022 (in thousands) Net cash provided by operating activities $ 73,425 $ 81,121 $ 87,212 Net cash provided by (used in) investing activities 22,314 (39,018) (81,371) Net cash provided by (used in) financing activities (73,478) (55,976) 4,036 Effect of foreign currency on cash (318) — — Net increase (decrease) in cash and cash equivalents $ 21,943 $ (13,873) $ 9,877 Operating Activities Our cash flows from operating activities are primarily influenced by growth in our operations, increases or decreases in collections from our buyers and related payments to our publishers, as well as our investment in personnel to support the anticipated growth of our business.
As a result, we continue to expect general and administrative expenses to increase in absolute dollars in future periods. Total Other Income (expense), Net Total other income (expense), net consists of interest income, unrealized gain (loss) on equity investment and other income (expense), net. Interest income is generated by investing excess cash into money market accounts and marketable securities.
Total Other Income (expense), Net Total other income (expense), net consists of interest income, unrealized gain (loss) on equity investment and other income (expense), net. Interest income is generated by investing excess cash into money market accounts and marketable securities.
Total Other Income (Expense), net Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) Total other income (expense), net $ (359) $ (5,267) $ 4,908 (93) % Total other income (expense), net increased for the year ended December 31, 2023, compared to the prior year period, primarily driven by impairment of our equity investment in 2022. 51 Table of Contents Provision for Income Taxes Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) Provision for income taxes $ 1,624 $ 8,762 $ (7,138) (81) % The difference between the effective tax rate in 2023 of 15% and the federal statutory income tax rate of 21% was primarily due to federal research and development credit and foreign derived intangible income (FDII) deduction partially offset by state taxes, stock-based compensation, and Section 162(m) limitation.
Other income (expense) also benefited from foreign currency fluctuations for the year ended December 31, 2024 compared to the prior year period. 51 Table of Contents Provision for Income Taxes Year Ended December 31, 2024 2023 $ Change % Change (dollars in thousands) Provision for income taxes $ 5,270 $ 1,624 $ 3,646 225 % The difference between the effective tax rate in 2024 of 30% and the federal statutory income tax rate of 21% was primarily due to state taxes, Section 162(m) limitation, and acquisition-related costs partially offset by foreign derived intangible income (FDII) deduction and federal research and development credit.
As of December 31, 2023, we had cash, cash equivalents, and marketable securities of $175.3 million and net working capital, consisting of current assets less current liabilities, of $182.4 million. As of December 31, 2023, we had retained earnings of $136.9 million.
As of December 31, 2024, we had cash, cash equivalents, and marketable securities of $140.6 million and net working capital, consisting of current assets less current liabilities, of $156.7 million.
For additional information regarding stock-based compensation and the assumptions used for determining the fair value of stock options and ESPP awards, refer to Note 2—Basis of Presentation and Summary of Significant Accounting Policies and Note 10—Stockholders’ Equity and Equity Incentive Plans. 56 Table of Contents Acquisition-related Intangible Assets and Goodwill Acquisition-related intangible assets with finite lives are amortized over their estimated useful lives on a straight-line basis, while goodwill amounts are not amortized.
For additional information regarding stock-based compensation and the assumptions used for determining the fair value of stock options and ESPP awards, refer to Note 2—Basis of Presentation and Summary of Significant Accounting Policies and Note 10—Stockholders’ Equity and Equity Incentive Plans.
For the year ended December 31, 2022, net cash provided by operating activities of $87.2 million resulted primarily from net income of $28.7 million, adjustments for non-cash expenses of $59.0 million, including $34.2 million for depreciation and amortization, $20.6 million for stock-based compensation, and $7.2 million for deferred income taxes, and an increase in accounts receivable of $24.4 million, partially offset by an increase in accounts payable of $29.8 million.
In addition, we expect seasonality to impact quarterly cash flows from operating activities. 53 Table of Contents For the year ended December 31, 2024, net cash provided by operating activities of $73.4 million resulted primarily from net income of $12.5 million, adjustments for non-cash expenses of $74.7 million, including $45.4 million for depreciation and amortization, $37.7 million for stock-based compensation, and $11.0 million for deferred income taxes, and an increase in accounts receivable of $49.3 million, partially offset by an increase in accounts payable of $38.1 million.
For the year ended December 31, 2022, we used $81.4 million of cash in investing activities, consisting of a net increase in investments of marketable securities of $4.4 million, $35.9 million in purchases of property and equipment (primarily data center infrastructure), $13.0 million of investments in capitalized internal use software, and $28.1 million for the Martin acquisition.
For the year ended December 31, 2024, net cash provided by investing activities was $22.3 million of cash, consisting of a net inflows from investments of marketable securities of $60.8 million, offset by $17.6 million in purchases of property and equipment (primarily data center infrastructure), and $20.9 million of investments in capitalized internal use software.
Contractual Obligations and Future Cash Requirements Our principal contractual obligations consist of non-cancelable leases for our various facilities.
Contractual Obligations and Future Cash Requirements Our principal contractual obligations consist of non-cancelable leases for our various facilities. In certain cases, the terms of the lease agreements provide for rental payments that increase over time.
We recognize revenue when a bid is won and a buyer purchases inventory on our platform. We estimate and record reductions to revenue for volume discounts based on expected volumes during the incentive term.
We recognize revenue when a bid is won and a buyer purchases inventory on our platform.
Interest income Year Ended December 31, 2023 2022 $ Change % Change (dollars in thousands) Interest income $ 8,828 $ 2,214 $ 6,614 299 % Interest income increased due to the increase in interest rates.
Interest income Year Ended December 31, 2024 2023 $ Change % Change (dollars in thousands) Interest income $ 8,477 $ 8,828 $ (351) (4) % Interest income decreased due to the decrease in interest rates and a decrease in holdings in marketable securities.
As of December 31, 2023, we had $4.5 million of long-term income tax liabilities, including interest, related to uncertain tax positions. Because of the high degree of uncertainty regarding the settlement of these liabilities, we are unable to estimate the years in which future cash outflows may occur.
Because of the high degree of uncertainty regarding the settlement of these liabilities, we are unable to estimate the years in which future cash outflows may occur. As a result, this amount is not included in the contractual obligations table above.
We expect revenue to continue to increase in 2024, with mobile and omnichannel video, which is the combination of short form video and OTT/CTV, as our primary growth drivers.
We expect revenue to continue to increase in 2025, primarily driven by growth in mobile and omnichannel video, which is the combination of short form video and OTT/CTV. Additionally, we expect our revenues to be affected by macroeconomic conditions, and will continue to be impacted by the bidding methodology changes implemented by one of our buyers in the near term.
Overall, our cost of revenue per impression processed in 2023 declined by 8% compared to 2022.
Overall, our cost of revenue per impression processed in 2024 decreased by 18% compared to 2023. Our gross margin of 65% in 2024 increased compared to 2023 of 63% due to revenue growth accelerating faster than cost of revenues.
In certain cases, the terms of the lease agreements provide for rental payments that increase over time. 54 Table of Contents The following table summarizes our contractual obligations, at December 31, 2023 (in thousands): Payments due by period Total Less than 1 year 1 - 3 years 3 - 5 years More than 5 years Other contractual obligations (1) $ 24,771 $ 18,314 $ 6,457 $ — $ — Operating lease liabilities 23,169 6,842 11,055 5,272 — Finance lease liabilities 646 145 302 199 — Total $ 48,586 $ 25,301 $ 17,814 $ 5,471 $ — ______________ (1) Other contractual obligations consist primarily of contractual obligations to third-party data center providers.
The following table summarizes our contractual obligations, at December 31, 2024 (in thousands): Payments due by period Total Less than 1 year 1 - 3 years 3 - 5 years More than 5 years Other contractual obligations (1) $ 25,487 $ 21,872 $ 3,615 $ — $ — Operating lease liabilities 57,902 6,513 18,178 9,125 24,086 Finance lease liabilities 501 149 311 41 — Total $ 83,890 $ 28,534 $ 22,104 $ 9,166 $ 24,086 ______________ (1) Other contractual obligations consist primarily of contractual obligations to third-party data center providers. 54 Table of Contents As of December 31, 2024, we had $5.0 million of long-term income tax liabilities, including interest, related to uncertain tax positions.