Combined with the Texas Partners acquisition, we will have 10 banking centers in the San Antonio area. I am pleased to announce that the Board of Directors approved increasing the fourth quarter 2025 dividend to $0.60 per share from $0.58 per share that was paid in the prior four quarters. The increase reflects the continued confidence the board has in our company and our markets. The compound annual growth rate in dividends declared from 2003 to 2025 was 10.7%.
We continue to share our success with our shareholders through the payment of dividends and opportunistic stock repurchases, while also continuing to grow our capital. Net income per diluted common share was $1.45 for the quarter ended September 30, 2025, compared with $1.34 for the same period in 2024, an increase of 8.2%. The net interest margin on a tax-equivalent basis was 3.24% for the three months ending September 30, 2025, compared with 2.95% for the same period in 2024. As mentioned in previous calls, our net interest margin should continue to improve over the next 24 to 36 months, with interest rates either increasing or decreasing 200 basis points.
Prosperity continues to exhibit solid operating metrics, with annualized return on tangible equity of 13.43% and return on assets of 1.44%. Our loans, excluding the warehouse purchase program loans, were $20.7 billion at September 30, 2025, compared with $20.9 billion at June 30, 2025, a decrease of $160 million or 77 basis points. We continue to work through credits acquired in previous mergers, and we are experiencing borrowers using their own cash to pay down balances or not drawing on their lines. Deposits were $27.7 billion at September 30, 2025, an increase of $308 million or 1.1%, 4.5% annualized from the $27.4 billion at June 30, 2025.