Gross profit for the twelve weeks ended February 11, 2023 was $1.9 billion, compared with $1.8 billion during the comparable prior year period. Gross profit, as a percentage of sales, was 52.3% compared to 53.0% during the comparable prior year period. The decrease in gross margin was impacted by a 27 basis point ($10.0 million) non-cash LIFO charge driven primarily by rising freight costs, with the remaining decrease resulting primarily from supply chain costs and accelerated growth in our commercial business.
Operating, selling, general and administrative expenses for the twelve weeks ended February 11, 2023 were $1.3 billion compared with $1.2 billion during the comparable prior year period. As a percentage of sales, these expenses were 34.1% compared with 34.4% during the comparable prior year period.
Net interest expense for the twelve weeks ended February 11, 2023, was $65.6 million compared with $42.5 million during the comparable prior year period. Average borrowings for the twelve weeks ended February 11, 2023 were $6.9 billion, compared with $5.6 billion for the comparable prior year period. Weighted average borrowing rates were 3.70% and 3.03% for the quarters ended February 11, 2023 and February 12, 2022, respectively.
Our effective income tax rate was 21.2% of pretax income for the twelve weeks ended February 11, 2023, and 19.3% for the comparable prior year period. The increase in the tax rate was primarily attributable to a decreased benefit from stock options exercised during the twelve weeks ended February 11, 2023. The benefit of stock options exercised for the twelve week period ended February 11, 2023 was $13.4 million compared to $23.4 million in the comparable prior year period.
Net income for the twelve weeks ended February 11, 2023 increased by $4.8 million to $476.5 million due to the factors set forth above, and diluted earnings per share increased by 10.5% to $24.64 from $22.30. Excluding the non-cash LIFO charge, adjusted net income increased 2.6% to $484.2 million, and adjusted diluted earnings per share increased 12.3% to $25.04. The impact on current quarter diluted earnings per share from stock repurchases since the end of the comparable prior year period was an increase of $0.42.
Twenty-Four Weeks Ended February 11, 2023
Compared with Twenty-Four Weeks Ended February 12, 2022
Net sales for the twenty-four weeks ended February 11, 2023 increased $637.4 million to $7.7 billion, or 9.1% over net sales of $7.0 billion for the comparable prior year period. Total auto parts sales increased by 9.1%, primarily driven by an increase in domestic same store sales of 5.5% and net sales of $147.1 million from new stores. Domestic commercial sales increased $245.1 million to $2.0 billion, or 14.1%, over the comparable prior year period.
Gross profit for the twenty-four weeks ended February 11, 2023 was $3.9 billion, compared with $3.7 billion during the comparable prior year period. Gross profit, as a percentage of sales, was 51.1% compared to 52.7% during the comparable prior year period. The decrease in gross margin was driven by a 119 basis point ($91.0 million) non-cash LIFO charge driven primarily by rising freight costs, with the remaining decrease resulting primarily from supply chain costs and accelerated growth in our commercial business.
Operating, selling, general and administrative expenses for the twenty-four weeks ended February 11, 2023, were $2.5 billion compared with $2.3 billion during the comparable prior year period. As a percentage of sales, these expenses were 33.0% compared with 33.1% during the comparable prior year period.
Net interest expense for the twenty-four weeks ended February 11, 2023, was $123.3 million compared with $85.8 million during the comparable prior year period. Average borrowings for the twenty-four weeks ended February 11, 2023 were $6.5 billion, compared with $5.4 billion for the comparable prior year period. Weighted average borrowing rates were 3.58% and 3.17% for the twenty-four week periods ended February 11, 2023 and February 12, 2022, respectively.
Our effective income tax rate was 20.0% of pretax income for the twenty-four weeks ended February 11, 2023, and 20.7% for the comparable prior year period. The decrease in the tax rate was primarily attributable to an increased benefit from stock options exercised during the twenty-four weeks ended February 11, 2023. The benefit of stock