Our balance sheet continues to get stronger, with cash and cash equivalents, other investments and marketable securities increasing 46% to $97.7 million as compared to $66.7 million at June 30, 2023, We have no debt and the net cash provided by operating activities for the twelve months ended June 30, 2024 was also strong, amounting to $45.4 million, an 84% increase over last year's level of 24.7 million.
Our Alarm Lock and Marks locking hardware lines continue to see growth in school and classroom security, healthcare, and retail loss-prevention, as well as in multi-dwelling commercial and residential applications. Locking sales in Q4 grew approximately 21% compared to last year and approximately 8% compared to Q3 and represents 71% of hardware sales. We continue to remain focused on further penetrating each of these markets.
Our recent introduction of Prima by NAPCO, a new All-in-One Panel for security, fire, video and connected home with a 5-minute installation, remains a very important focus to the Company. Our goal is for Prima to address an important mass segment of the security market, including residential and small business systems. With built-in Wi-Fi/cellular radio communications, customer alert notifications, and video and smart home subscription options for each installed system, the security dealer, as well as the Company, can add more recurring service revenue generating accounts.
NAPCO's record results for Q4 and fiscal year 2024, was primarily the result of the continued growth and profitability from recurring service revenues as well as the strong sales from our Alarm Lock and Marks locking product lines. Radio sales were down 5% sequentially and 10% as compared to Q4 last year due to the continued effect of the sunsetting of 3G technology and existing radio inventory levels at some of our distributors. Radios represent 59% of Intrusion and Access Alarm Products sales and we expect inventory levels at distributors to continue to reduce and radio sales to continue to be a key contributor to our hardware sales and lead to the continued growth of our highly profitable recurring service revenues."
Mr. Soloway concluded, "Fiscal 2024 was an amazing record-breaking year where we generated net income of $49.8 million, Adjusted EBITDA* of $58.9 million and an Adjusted EBITDA* margin of 31%. But as I have said before, there is more work to be done. While we continue to be encouraged with the gross margin for hardware sales of 31.4%, we believe this should improve further in fiscal 2025 and beyond. Our strong net income Adjusted EBITDA* and growing cash, indicate the financial strength of our business. As such, we are pleased to continue our dividend program and we will be increasing the quarterly dividend to $0.125 per share payable on September 24, 2024. As always, we will strive to accomplish our goal of continued financial strength, product innovation, technical superiority, and strong profitability, for fiscal 2025 and beyond".
Financial Results
Net sales for the quarter increased 13% to $50.3 million (the highest quarterly sales in the Company's history), as compared to $44.6 million for the same period one year ago. Net sales for the year ended June 30, 2024 increased 11% to a twelve month record $188.8 million, as compared to $170 million for the same period one year ago. Research and development costs for the quarter increased 28% to $3.0 million, or 6% of net sales, as compared to $2.4 million or 5% of net sales for the same period a year ago. Research and development costs for the year ended June 30, 2024 increased 15% to $10.8 million, or 6% of net sales, as compared to $9.3 million or 5% of net sales for the same period a year ago. Selling, general and administrative expenses for the quarter increased 22% to $10.9 million or 22% of net sales, as compared to $8.9 million, or 20% of net sales for the same period last year. Selling, general and administrative expenses for the year ended June 30, 2024 increased 11% to $37.1 million or 20% of net sales, as compared to $33.6 million, or 20% of net sales for the same period last year.
Operating income for the quarter increased 18% to $14.0 million as compared to $11.8 million for the same period last year. Operating income for the year ended June 30, 2024 increased 77% to $53.8 million as compared to $30.3 million for the same period last year. Net income for the quarter increased 28% to a quarterly record $13.5 million, or $0.36 per diluted share, as compared to $10.6 million, or $0.28 per diluted share, for the same period last year and represents 27% of net sales. Net income for the year ended June 30, 2024 increased 84% to a twelve month record of $49.8 million or $1.34 per diluted share as compared to $27.1 million or $0.73 per diluted share for the same period last year and represents 26% of net sales.
Adjusted EBITDA* for the quarter increased 18% to $15.4 million, or $0.41 per diluted share, as compared to $13.0 million, or $0.35 per diluted share for the same period last year and equates to an Adjusted EBITDA* margin of 31%. Adjusted EBITDA* for the twelve months ended June 30, 2024 increased 72% to a record $58.9 million, or $1.59 per diluted share, as compared to $34.3 million, or $0.93 per diluted share for the same period last year and equates to an Adjusted EBITDA* margin of 31%.
Balance Sheet Summary
As of June 30, 2024, the Company had $97.7 million in cash and cash equivalents, other investments and marketable securities as compared to $66.7 million as of June 30, 2023. Working capital (defined as current assets less current liabilities) was $146.5 million at June 30, 2024 as compared with working capital of $111.7 million at June 30, 2023. Current ratio (defined as current assets divided by current liabilities) was 7.6:1 at June 30, 2024, and 6.7:1 at June 30, 2023.
