Roop K. Lakkaraju
Executive Vice President & Chief Financial Officer at Bio-Rad Laboratories
Thank you, Andy. I'd now like to review the results for the first quarter. Net sales for the first quarter of 2024 was $611 million, which is a 9.8% decline on a reported basis versus $677 million in Q1 of 2023. On a currency-neutral basis, the year-over-year revenue decline was 9.6%. As Andy mentioned, the year-over-year decline was primarily the result of ongoing weakness in key Life Science end markets, somewhat offset by steady growth of the Clinical Diagnostics Group. Sales of the Life Science Group in the first quarter of 2024 were $242 million compared to $324 million in Q1 of 2023 which is a decrease of 25.3% on a reported basis and a decline of 25.2% on a currency-neutral basis. The year-over-year decline impacted most product and geographic areas. Excluding Process Chromatography sales, which can fluctuate quarter-to-quarter, Life Science Group revenue decreased 16.6% on a currency-neutral basis.
Sales of the Clinical Diagnostics Group in the first quarter were $369 million compared to $352 million in Q1 of 2023, which is an increase of 4.7% on a reported basis and 4.8% on a currency-neutral basis. Growth of the Clinical Diagnostics group was primarily driven by increased demand for quality controls, blood typing and diabetes. The geographic basis, currency-neutral year-over-year revenue for the Diagnostics group posted balanced growth across all three regions. For the company, Q1 reported GAAP gross margin of 53.4% as compared to 53.5% in the first quarter of 2023 was in line with our expectations as we maintained a tight focus on manufacturing costs, which was partially offset by higher material costs and lower absorption. Amortization related to prior acquisitions recorded and cost of goods sold was approximately $4 million in both periods. SG &A expenses for Q1 2024 were $215 million or 35.2% of sales compared to $226 million or 33% in Q1 of 2023.
The decrease in SG &A spend was driven by the positive impact of our previously discussed cost reduction initiatives including lower employee-related expenses and discretionary spend as well as higher restructuring charges in the year ago period. Total amortization expense related to acquisitions recorded in SG &A for the quarter is approximately $1 million versus approximately $2 million in Q1 of 2023. Research and development expense in the first quarter was $66 million or 10.9% of sales compared to $75 million or 11.1% of sales in Q1 of 2023. The year-over-year decrease was primarily due to decreased employee-related expenses and lower restructuring costs. Q1 operating income was $45 million or 7.3% of sales compared to $62 million or 9.1% of sales in Q1 of 2023, primarily due to lower sales versus the year ago period, which were partially offset by our expense management initiatives.
Looking below the operating line, the change in fair market value of equity security holdings, which are substantially related to Bio-Rad's ownership of Sartorius AG shares added $422 million of income to the reported results. During the quarter, interest and other income resulted in net other income of $24 million compared to net other income of $40 million last year. The primary driver of the year-over-year change is the lower Sartorius dividend, which declined to $18 million in Q1 of 2024 versus the quarter of 2023. The effective tax rate for the first quarter of 2024 was 21.8% compared to 18.7% for the same period in 2023. The effective tax rate reported in these periods was primarily affected by the accounting treatment of our equity securities. First quarter reported net income was $384 million or $13.45 diluted earnings per share compared to net income of $69 million or a diluted earnings per share of $2.32 in Q1 of 2023.
This change from last year is largely related to changes in the valuation of our Sartorius Holdings. Moving on to the non-GAAP results. Looking at the results on a non-GAAP basis, we have excluded certain atypical and unique items that impacted both the gross and operating margins as well as other income. These items are detailed in the reconciliation table in the press release. Looking at the non-GAAP results for the first quarter. In cost of goods sold, we have excluded approximately $4 million of amortization of purchased intangibles of approximately $1 million of restructuring expenses. These exclusions moved to non-GAAP gross margin to 54.2% for the first quarter of 2024, which is flat to Q1 of 2023. Non-GAAP SG &A dollar spend was slightly lower on a year-over-year basis, but as a percentage of sales was higher due to lower revenue from Q1 '24, specifically in the first quarter of '24. SG &A as a percent was 34% versus 31.3% in Q1 of 2023.
In SG &A, on a non-GAAP basis, we have excluded the amortization of intangibles of approximately $1 million approximately $2 billion for an in vitro diagnostic registration fee in Europe for previously approved products and approximately $4 million of restructuring-related expenses. Non-GAAP R &D as a percentage of sales in the first quarter of 2024 was 10.5% versus 10.4% in Q1 of 2023. In R &D, on a non-GAAP basis, we have excluded approximately $2 million of restructuring expenses and a small acquisition expense. The cumulative sum of these non-GAAP adjustments result in moving the quarterly operating margin from 7.3% on a GAAP basis to 9.7% on a non-GAAP basis. This non-GAAP operating margin compares to non-GAAP operating margin of 12.4% in Q1 of 2023. We've also excluded certain items below the operating line, which is primarily related to the increase in value of the Sartorius Equity Securities and loan receivable holdings of $422 million.
The non-GAAP effective tax rate for the first quarter of 2024 was 22.3% compared to 20.9% for the same period in 2023. A higher rate in 2024 was driven by geographical mix of earnings and change in valuation allowance related to our deferred tax assets. Finally, non-GAAP net income for the first quarter of 2024 was $65 million or $2.29 diluted earnings per share compared to $99 million or a diluted earnings per share of $3.34 in Q1 of 2023. Moving on to the balance sheet. Total cash and short-term investments at the end of Q1 2024 was $1.651 billion compared to $1.613 billion at the end of 2023. The change in cash and short-term investments from the fourth quarter of 2023 was primarily due to the change in working capital. Inventory of $783 million was essentially flat compared to $781 million in the prior quarter. For the first quarter of 2024, net cash generated from operating activities was $70 million, which compares to $98 million in Q1 of 2023.
Net capital expenditures for the first quarter of 2024 were $40 million, and depreciation and amortization was $37 million. Adjusted EBITDA for the first quarter of 2024 was $109 million or 17.8% of sales and excluding the Sartorius dividend, was 14.8%. The adjusted EBITDA for the first quarter of 2023 was $149 million or 21.9% of sales and excluding the Sartorius dividend was 16.8%. During the first quarter, we purchased 14,250 shares of our stock for a total cost of approximately $5 million or an average purchase price of approximately $330 per share. We continue to be opportunistic with our buyback program and still have approximately $275 million available for share repurchases under the current Board authorized program.
Moving on to the non-GAAP guidance. As referenced in Andy's commentary, we are seeing some encouraging signs in the Life Science end markets. However, we remain cautious on the magnitude and timing of the recovery for the Life Science Group but are still anticipating improvement during the second half of the year. We continue to expect normalized growth for the Clinical Diagnostics group in 2024. Taken together, we are maintaining our full year outlook with currency-neutral revenue growth to be between 1% and 2.5% and non-GAAP operating margin projected to be between 13.5% and 14%.
I'll now hand the call back to Norman to make a few concluding remarks.