March 31, 2024, compared to 60% and 81% as of December 31, 2023 and March 31, 2023, respectively. Brokered deposits accounted for 36% of total deposits as of March 31, 2024, compared to 40% and 19% as of December 31, 2023 and March 31, 2023, respectively.
Cost of deposits increased to 3.63% for the quarter, compared to 3.41% for the prior quarter and 2.38% for the first quarter of 2023.
Insured and collateralized deposits accounted for approximately 85% of total deposits as of March 31, 2024, compared to 87% from the prior quarter.
Our loan to deposit ratio measured 94.8% as of March 31, 2024, compared to 95.2% and 106.1% as of December 31, 2023 and March 31, 2023, respectively.
Borrowings were $1.7 billion as of March 31, 2024, compared to $1.4 billion and $2.1 billion as of December 31, 2023 and March 31, 2023, respectively. Average borrowings outstanding were $1.6 billion or 11.8% of total average assets for the quarter, compared to $1.1 billion or 8.7% of total average assets for the prior quarter and $1.2 billion or 9.2% for the first quarter of 2023. The increased average borrowings from the prior quarter were used to enhance on-balance sheet liquidity, as cash and cash equivalents as a percentage of total assets increased to 11.7% as of March 31, 2024 from 10.0% as of December 31, 2023.
As of March 31, 2024, our unused borrowing capacity was $2.6 billion, which consists of available lines of credit with FHLB and other correspondent banks as well as access to the Federal Reserve Bank’s discount window.
Private Wealth Management and Trust Assets
AUM was $5.5 billion as of March 31, 2024, compared to $5.2 billion as of December 31, 2023 and March 31, 2023. The net change in AUM balance of $0.2 billion from the prior quarter is comprised of the following: $69 million of new accounts; $61 million of net withdrawals; and $209 million of performance gains. AUA at FFB’s Trust Department was $1.2 billion as of March 31, 2024, compared to $1.3 billion as of December 31, 2023 and March 31, 2023.
Net Interest Income and Net Interest Margin
Net interest income was $38.4 million for the quarter, compared to $42.5 million for the prior quarter and $58.8 million for the first quarter of 2023. Interest income totaled $150.5 million for the quarter, compared to $146.6 million for the prior quarter and $137.0 million for the first quarter of 2023. The increase in interest income compared to the prior quarter was due to an increase in the average interest-earning asset balances as well as an increase in the average yields earned on such balances. Average interest-earning asset balances totaled $13.0 billion for the quarter, compared to $12.7 billion for both the prior quarter and first quarter of quarter of 2023. Yields on interest-earning assets averaged 4.64% for the quarter, compared to 4.62% for the prior quarter and 4.32% for the first quarter of 2023.
Interest expense was $112.1 million for the quarter, compared to $104.1 million for the prior quarter and $78.2 million for the first quarter of 2023. The increase in interest expense compared to the prior quarter was due to an increase in average interest-bearing liability balances as well as an increase in the average rates paid on such balances. Average interest-bearing liability balances, consisting of interest-bearing deposits, borrowings, and subordinated debt, totaled $10.6 billion for the quarter, compared to $9.9 billion for the prior quarter and $9.3 billion for the first quarter of 2023. Rates on interest-bearing liability balances averaged 4.24% for the quarter, compared to 4.19% for the prior quarter and 3.41% for the first quarter of 2023. Rates on interest-bearing deposits averaged 4.28% for the quarter, compared to 4.21% for the prior quarter and 3.19% for the first quarter of 2023.