Cost of goods sold increased $41.4 million, or 59%, to $111.8 million, as compared to $70.5 million for the second quarter of 2020 and is primarily attributable to the increase in product sales. Gross profit for the thirteen weeks ended June 27, 2021 increased $26.4 million, or 48.1%, to $81.2 million, as compared to $54.8 million for the second quarter of 2020. The increase in gross profit was driven by the increase in sales. Gross margin for the thirteen weeks ended June 27, 2021 was 42.1% compared to a gross margin of 43.8% for the thirteen weeks ended June 28, 2020.
Selling, general and administrative costs for the quarter increased $9.9 million to $26.2 million, representing an increase of 61% when compared to $16.3 million in 2020. Incremental SG&A from recent acquisitions were responsible for $5.3 million of the increase in the quarter. Additional cost drivers include a $1.6 million increase in shipping costs related to higher sales and global supply chain pressure, higher audit fees associated with the business combination with Empower, and increases in software licensing that support Holley’s growth.
R&D and other operating expenses provided leverage in the second quarter, as those expenses increased 26% and 20%, respectively, against the net sales increase of 54%. Increases in these other operating expense areas are primarily due to acquisitions.
Net income for the second quarter 2021 reflects higher sales volume and the leverage achieved on certain fixed expenses. Net income improved to $23.1 million in the second quarter compared to $12.5 million in 2020, an increase of 85%.
Adjusted EBITDA grew from $36.4 million in the second quarter last year to $54.1 million in the second quarter of 2021, representing 49% year-over-year growth. Reconciliation to GAAP Net Income is included in the “Use and Reconciliation of Non-GAAP Financial Measures” table below.
Significant Event Subsequent to Quarter End
On July 16, 2021, Holley completed the business combination with Empower LTD and became a publicly traded company on the New York Stock Exchange (NYSE: HLLY). Since the transaction closed in Holley’s third fiscal quarter, the 10-Q Holley will file with the Securities and Exchange Commission for the second quarter will reflect the pre-combination results of Empower LTD.
Fiscal 2021 Full Year Outlook
We reiterate our full-year expectations of recognized net sales in the range of $648 to $663 million for fiscal 2021. We expect pro forma net sales in the range of $655 to $670 million, and pro forma adjusted EBITDA between $165 and $170 million. Additional information regarding pro forma adjustments is included in the “Use and Reconciliation of Non-GAAP Financial Measures” table below.
Dominic Bardos, Holley’s Chief Financial Officer, added, “We continued to execute on our strategy in the second quarter, with both organic growth and recent acquisitions contributing to our strong revenue performance. We expect sales growth to moderate in the back half of 2021, largely due to lapping strong 2020 performance and the three acquisitions made during the fourth quarter last year. Our full-year guidance also contemplates the uncertainties surrounding global supply chain challenges and inflationary pressure on raw material costs. Our markets remain strong and our consumers continue to be highly engaged.”