Pamela Bentley
Analyst · JPMorgan
Thanks, Jon. Before we get into our performance this quarter, I want to briefly address the SEC statement on warrant accounting and its impacts on our GAAP fourth quarter results in the amended 10-K that was filed earlier this week. As a result of the SEC statement, we determined that based on the tender features of our warrants, they should be classified as liabilities and mark-to-market each reporting period. Based on the change in our warrant fair value, from the time of the public offering through the end of December, we recorded a nonoperating expense of $13 million in the fourth quarter. The fair value of the warrant subsequently declined in the first quarter resulting in a more than offsetting $14 million of nonoperating income. These changes did not impact our non-GAAP financial measures or cash position, and they will not be impacted going forward.
Turning to our performance in the quarter. I'll begin on Slide 8. As Michael noted, we are very pleased to see the investments we've made in recent years continue to come to fruition and benefit our assets under management and financial performance. On a year-over-year basis, our fee-related earnings, adjusted EBITDA and adjusted net income all increased, illustrating the continued positive momentum of our business.
Fee-paying assets under management grew 12% over the prior year and grew 3% from the fourth quarter, which portends solid growth for the second quarter. Going one level deeper, fee-paying assets under management and management fees grew for both private markets and absolute return strategies. We also saw stable average fee rates across the business this quarter and expect this fee stability to continue.
This quarter, our catch-up management fees related to our specialized fund fundraising included in our fee-related revenue were $1.5 million, which is approximately $1 million higher than last quarter. As we continue to raise our specialized funds, we will see ongoing catch-up management fees and expect them to be higher in the third and fourth quarters and continue into next year.
Regarding incentive fees, as Michael noted, we received $6 million in annual performance fees in the quarter, related primarily to a specific program that crystallizes its fees on March 31 of each year. As you saw last quarter, the vast majority of our annual performance fees crystallized in the fourth quarter. And other than a few accounts, we expect that to continue to be the case.
Turning to our operating expenses. As we have previously discussed, they increased in line with our expectations. I mentioned on our fourth quarter call that some of our compensation-related costs are seasonal in nature. During the first quarter, the combined impact of timing of our bonus payments, payroll taxes and 401(k) contributions drove $2.5 million of higher expenses over the fourth quarter. Headcount was relatively stable in the first quarter. We expect headcount and compensation to increase throughout the year as we continue to invest in public company-related personnel and make strategic investments in certain business development professionals.
As also mentioned on last quarter's call, in March, we granted 4.8 million restricted stock units related to our public offering. This transaction-related grant saw 2 million shares left in March, with the remaining 2.8 million shares scheduled to vest over the next 2 years. This resulted in $27 million of GAAP compensation expense relating to the restricted stock units in the first quarter.
Our general administrative expenses increased by $2 million in the first quarter, in line with our expectations and consistent with our fee-related earnings goals. As Michael mentioned, we are on track for our target fee-related revenue growth of 12% to 15% and fee-related earnings growth of 15% to 20% for 2021, with our growth accelerating through the remainder of the year. We continue to deploy capital and raise additional capital across the firm, including in our specialized funds.
As illustrated on Slide 10, our embedded revenue from annual incentive fees, largely within our ARS vertical, continues to increase and provide significant opportunity for future revenue and earnings growth. The potential value from annual performance fees has nearly doubled over the last 4 years and is now above $41 million on a run rate basis.
Our carried interest position has also continued to grow and diversify over time. We enjoy considerable carry dollars at work, which are not yet reflected in unrealized carry and will provide incentive fee earnings power for the future. At quarter end, we had $491 million in unrealized carried interest, which is a 29% increase over the first quarter of 2020. As a reminder, our carried interest pool is unique in its very high level of diversification. Our unrealized carry is spread amongst 121 programs and dozens of contributing investments.
Today, the majority of aggregate unrealized carry has been contractually awarded to employees or transferred as a part of Mosaic, which was an opportunistic transaction completed early last year, where most of our balance sheet investments and our rights to carried interest were transferred to a third party in exchange for cash. As Michael discussed, given the significant value in its rights to future carry and investments, we intend to exercise our option to repurchase Mosaic by year-end. We anticipate the repurchase will be accretive.
Turning to Slide 14. Our cash balance at quarter end was $156 million. Alongside the amendment and extension of our term loan and revolving credit facility in February, we used proceeds from going public to pay down an additional $50 million of debt and in the process, reduced our interest rate. As a result, our quarterly interest expense is expected to be closer to $3 million starting in the second quarter of this year compared to $4.5 million in the first quarter. We also generated over $20 million in cash from the exercise of 1.8 million warrants in the first quarter.
In summary, our strong performance demonstrates the culmination of our platform expansion efforts as well as an exciting preview of our future growth. Given industry tailwinds, a robust fundraising pipeline and multiple avenues to grow our assets, combined with our scalable platform, we are excited about the future momentum of the business.
We're now happy to take any questions.