J. Eric Bjornholt
Chief Financial Officer, Senior Vice President at Microchip Technology
Thank you. Thanks, Steve, and good afternoon, everyone. We are including information in our press release and in this conference call on various GAAP and non-GAAP measures. We have posted a full GAAP to non-GAAP reconciliation on the Investor Relations page of our website at www.microchip.com and included reconciliation information in our earnings press release, which we believe you will find useful when comparing our GAAP and non-GAAP results. We've also posted a summary of our outstanding debt and our leverage metrics on our website. I will now go through some of the operating results, including net sales, gross margin and operating expenses.
Other than net sales, I will be referring to these results on a non-GAAP basis, which is based on expenses prior to the effects of our acquisition activities, share-based compensation and certain other adjustments as described in our earnings press release and in the reconciliations on our website. Net sales in the December quarter were $1.026 billion, which was down 11.8% sequentially. We have posted a summary of our net sales by-product line and geography on our website for your reference.
On a non-GAAP basis, gross margins were 55.4%, including capacity underutilization charges of $42.7 million as we are aggressively managing production activities to adjust to challenging business conditions. Operating expenses were at 34.9% of net sales and operating margin was 20.5%. Non-GAAP net income was $107.3 million and non-GAAP earnings per diluted share was $0.20. Please note that our operating expenses increased in the December quarter and will further increase in the March quarter due to a predominant portion of our employees coming off the pay cut that we had spent on for about nine months in the late November, early December 2024 timeframe. The full quarterly impact of this is reflected in our operating expense guidance for the March quarter.
On a GAAP basis in the December quarter, gross margins were 54.7%. Total operating expenses were $530.5 million and included acquisition intangible amortization of $122.6 million, special charges of $3.5 million and share-based compensation of $42 million and $4.3 million of other expenses. The GAAP net loss was $53.6 million, resulting in a loss per share of $0.10. Our non-GAAP cash tax-rate was 19.9% in the December quarter. We currently expect our non-GAAP cash tax-rate to be approximately 14.5% for the 4th-quarter of fiscal year 2025, which is modestly higher than our previously forecasted 13% tax-rate. This is a result of expected overpayments in two of our larger tax jurisdictions, which will have the impact of reducing our fiscal year 2026 tax-rate as we are calculating this on a cash basis.
Our non-GAAP cash tax-rate is exclusive of the transition tax and any tax audit settlements related to taxes accrued in prior fiscal years. Our inventory balance at, 31, 2024 was $1.356 billion, which was up $16.7 million from the end-of-the September 2024 quarter. We had 266 days of inventory at the end-of-the December quarter, which was up 19 days from the prior quarter's level. At the midpoint of our March 2025 quarterly guidance, we would expect both inventory dollars and inventory days to decrease from the December 31 December 2024 levels. We also continue to invest in-building inventory for long-lived high-margin products whose manufacturing capacity is being end-of-life by our supply-chain partners and these last-time buys represented 18 days of inventory at the end of December.
Inventory at our distributors in the December quarter was at 37 days and was down three days from the prior quarter's level. Distribution took down their inventory holdings in the December quarter as distribution sell-through was $118 million higher than distribution sell-in. Our cash-flow from operating activities was $271.5 million in the December quarter. Our adjusted free-cash flow was $244.6 million in the December quarter. As of December 31, our consolidated cash and total investment position was $586 million, which is higher-than-normal due to the timing of the maturity dates of some of our commercial paper that did not occur until early-January, which was used to pay-down debt after the end-of-the December quarter. We retired $665.5 million in convertible bonds that matured in November 2024.
In the December quarter, we also issued $1 billion in investment-grade bonds with a 4.9% coupon maturing in March of 2028 and $1 billion in investment-grade bonds with a 5.05% coupon maturing in February 2030. We used the proceeds of these bond offerings to retire a $750 million term-loan and pay-down a portion of our commercial paper balance. Our next debt maturity is a $1.2 billion bond maturing -- maturing in September 2025. The debt issuance this past quarter will give us ample room to retire our September 2025 bond with our line-of-credit or commercial paper programs. As a result, we have taken the refinancing risks off the table for the $1.2 billion maturity. Our net-debt increased by $33.6 million in the December quarter.
Our adjusted EBITDA in the December quarter was $274.9 million and 26.8% of net sales. Our trailing 12-month adjusted EBITDA was $1.64 billion. Our net-debt to adjusted EBITDA was 3.78 at December 31 December 2024, up from 1.27 at December 31, 2023. Capital expenditures were $18.1 million in the December quarter. Our expectation for capital expenditures for fiscal year '25 is about $135 million and we expect fiscal year 2026 capital expenditures to be lower than that as we have a lot of capacity to grow back into as well as capital that we purchased during the upcycle that has not been placed in-service yet. Depreciation expense in the December quarter was $40.4 million.
I will now turn it over to Rich, who will provide some commentary on our product-line innovations in the December quarter. Rich?