Total operating expenses for the fourth quarter of 2020 were $83.3 million, an increase from $27.9 million in the fourth quarter of 2019, primarily due to a $53.1 million increase in stock-based compensation expense related to accelerated stock vesting at the IPO.
Net loss for the fourth quarter of 2020 was ($54.4) million, an increase from ($6.0) million of net loss in the fourth quarter of 2019, primarily due to a $61.6 million increase in stock-based compensation expense related to accelerated stock vesting at the IPO. Diluted Earnings Per Share for the fourth quarter 2020 was ($0.40) compared to ($0.05) for the fourth quarter of 2019.
Adjusted EBITDA for the fourth quarter of 2020 was $22.2 million compared to $16.3 million for the fourth quarter of 2019.
Adjusted Net Income for the fourth quarter of 2020 was $11.8 million compared to an Adjusted Net Loss of ($3.7) million for the fourth quarter of 2019. Adjusted Diluted Earnings Per Share for the fourth quarter 2020 was $0.09 compared to ($0.03) for the fourth quarter of 2019. See note (2) in the section A Note on Non-GAAP Financial Measures, below, for more information on Adjusted Net Income and Adjusted Diluted Earnings Per Share.
Full Year 2020 Results
Total revenue for the full year ended December 31, 2020 was $243.5 million, representing 17% growth over 2019. The revenue growth was driven by growth in our technology enabled services and software product offerings due to strong renewal rates and client expansions.
Total cost of revenues for the full year of 2020 was $100.8 million, an increase from $79.8 million for the full year of 2019, primarily due to increased billable headcount, performance-based employee compensation and an $8.6 million increase in stock-based compensation expense primarily due to accelerated vesting relating to the IPO.
Total operating expenses for the full year of 2020 were $167.2 million, an increase from $109.1 million for the full year of 2019, primarily due to a $54.2 million increase in stock-based compensation expense related to accelerated stock vesting at the IPO.
Net loss for the full year of 2020 was ($49.4) million, an increase from ($8.9) million of net loss in the full year of 2019. This was primarily due to a $62.8 million increase in stock-based compensation expense related to accelerated stock vesting at the IPO. Diluted Earnings Per Share for the full year 2020 was ($0.37) compared to ($0.07) for the full year of 2019.
Adjusted EBITDA for the full year 2020 was $87.9 million compared to $68.4 million for 2019.
Adjusted Net Income for the full year 2020 was $22.0 million compared to $0.8 million for 2019. Adjusted Diluted Earnings Per Share for 2020 was $0.17 compared to $0.01 for 2019.
Cash and cash equivalents were $271.4 million as of December 31, 2020, and total debt outstanding net of debt issuance costs was $298.8 million after the voluntary repayment of $80 million of long-term debt in the fourth quarter. The current debt structure does not include any significant maturity until 2024.