$614.9 million, or 50.9% of our total loan portfolio at December 31, 2023. We remain focused on prudently growing our Litigation-Related loan portfolio as our regional Business Development Officers (“BDOs”) and related support staff continue to drive growth across our national commercial platform. We also had Commercial Litigation-Related committed and uncommitted undrawn lines of credit totaling $91.1 million and $577.3 million, respectively, at September 30, 2024.
Debt Securities Portfolio. Securities available-for-sale increased $89.4 million, or 73.2%, to $211.5 million at September 30, 2024 from $122.1 million at December 31, 2023, due to our current balance sheet management strategy of deploying funds in short duration agency mortgage-backed securities at peak market interest rates, while simultaneously moderating multifamily and commercial real estate (“CRE”) growth due to the current economic and interest rate environment. The increase was driven by purchases of $102.7 million, and unrealized gains of $4.0 million, partially offset by paydowns of $17.2 million. Securities held-to-maturity decreased $6.2 million, or 8.1%, to $70.8 million at September 30, 2024 from $77.0 million at December 31, 2023, driven by paydowns of $6.1 million and net premium amortization of $77 thousand.
Funding. Total deposits increased $129.1 million, or 9.2%, to $1.54 billion at September 30, 2024 from $1.41 billion at December 31, 2023. We continue to focus on the acquisition and expansion of core deposit relationships. Core deposits, which we define as total deposits excluding time deposits, totaled $1.52 billion at September 30, 2024, or 99.1% of total deposits, compared to $1.40 billion or 99.4% of total deposits at December 31, 2023. Litigation and payment processing deposits represent $1.27 billion, or 82.9%, of total deposits at September 30, 2024. Savings, NOW and money market deposits increased $56.6 million, or 6.1%, to $982.8 million at September 30, 2024.
Core commercial relationship banking clients in our two national verticals represent approximately 80% of our $1.54 billion deposit base at September 30, 2024. These relationship banking clients are derived from coupling lending facilities, payment processing, and other unique custodial banking needs with commercial cash management depository services. Our deposit strategy primarily focuses on developing full service commercial banking relationships with our clients through lending facilities, payment processing, and other unique commercial cash management services in our two national verticals, rather than competing with other institutions on rate. Our longer duration interest on lawyer trust accounts (“IOLTA”), escrow and claimant trust settlement deposits represent $828.9 million, or 54.0%, of total deposits. As of September 30, 2024, uninsured deposits were $458.9 million, or 30%, of our total deposits of $1.54 billion, excluding $10.6 million of affiliate deposits held by the Bank. Approximately 80% of our uninsured deposits represent clients with full relationship banking (loans, payment processing, and other service-oriented relationships) including, but not limited to, law firm operating accounts, law firm IOLTA/escrow accounts, merchant reserves, ISO reserves, ACH processing, and custodial accounts.
Due to the nature of our larger mass tort and class action settlements related to the litigation vertical, we participate in FDIC insured sweep programs as well as treasury secured money market funds. As of September 30, 2024, off-balance sheet sweep funds totaled approximately $488.0 million, of which approximately $356.5 million, or 73.1%, was available to be swept onto our balance sheet as reciprocal client relationship deposits. Our deposit growth and off-balance sheet funds continue to demonstrate our highly efficient branchless and technology enabled deposit platforms.
At September 30, 2024, we had the ability to borrow a total of $395.8 million from the Federal Home Loan Bank of New York. We also had an available line of credit with the Federal Reserve Bank of New York discount window of $54.9 million. No borrowing amounts were outstanding as of September 30, 2024. Historically, we have never leveraged our balance sheet to generate earnings and have always utilized core client deposits to fund our asset growth and related earnings.
Stockholders’ Equity. Total stockholders’ equity increased $34.0 million to $232.6 million at September 30, 2024, from $198.6 million at December 31, 2023, primarily due to net income of $31.9 million and decreases in other comprehensive losses of $2.9 million, as unrealized losses on our securities available-for-sale declined due to current short-term market interest rates, and amortization of share-based compensation of $2.9 million, partially offset by dividends declared to common stockholders of $3.7 million.
Asset Quality. Nonperforming assets consisted of one multifamily loan totaling $10.9 million as of September 30, 2024 and December 31, 2023. We had no exposure to commercial office space, no construction loans, and $14.8