OG&A expenses, as a percentage of sales, were 17.01% for the first two quarters of 2019, compared to 16.69% for the first two quarters of 2018. The increase in the first two quarters of 2019, compared to the first two quarters of 2018 resulted primarily from the 2019 OG&A Adjusted Items, the 2018 OG&A Adjusted Item, the effect of decreased supermarket fuel and convenience store sales, which increases our OG&A rate, as a percentage of sales, investments in our digital strategy and increases in hourly associate labor costs attributed to investing in higher wages and other comprehensive benefits to improve employee retention, engagement and customer experience, partially offset by the execution of Restock Kroger initiatives that drive administrative efficiencies, store productivity and sourcing cost reductions, planned real estate transactions during the first quarter of 2019 and decreased incentive plan costs. Excluding the effect of fuel, the 2019 OG&A Adjusted Items and the 2018 OG&A Adjusted Item, our OG&A rate decreased 13 basis points in the first two quarters of 2019, compared to the first two quarters of 2018. This decrease resulted primarily from the execution of Restock Kroger initiatives that drive administrative efficiencies, store productivity and sourcing cost reductions, planned real estate transactions during the first quarter of 2019 and decreased incentive plan costs, partially offset by investments in our digital strategy and increases in hourly associate labor costs attributed to investing in higher wages and other comprehensive benefits to improve employee retention, engagement and customer experience.
During the second quarter of 2019, we accepted an offer to sell an unused warehouse that had been on the market for some time. We used this gain as an opportunity to contribute a similar amount into the UFCW Consolidated Pension Plan, helping stabilize associates’ future benefits. The net impact of these transactions had no effect to OG&A for the second quarter and first two quarters of 2019.
Rent Expense
Rent expense, as a percentage of sales, remained relatively consistent in both the second quarter and first two quarters of 2019, compared to the same periods in 2018.
Depreciation and Amortization Expense
Depreciation and amortization expense increased, as a percentage of sales, in the second quarter of 2019, compared to the second quarter of 2018. This increase is primarily due to lower fuel sales, which increases our depreciation expense as a percentage of sales, and additional depreciation on capital investments, excluding mergers and lease buyouts, of $3.0 billion, during the rolling four quarter period ending with the second quarter of 2019.
Depreciation and amortization expense increased, as a percentage of sales, in the first two quarters of 2019, compared to the first two quarters of 2018. This increase is primarily due to lower fuel sales, which increases our depreciation expense as a percentage of sales, the 2018 Depreciation Adjusted Item and additional depreciation on capital investments, excluding mergers and lease buyouts, of $3.0 billion, during the rolling four quarter period ending with the second quarter of 2019.
Operating Profit and FIFO Operating Profit
Operating profit was $559 million, or 1.98% of sales, for the second quarter of 2019, compared to $549 million, or 1.96% of sales, for the second quarter of 2018. Operating profit, as a percentage of sales, increased 2 basis points in the second quarter of 2019, compared to the second quarter of 2018, due to a higher gross margin rate, partially offset by increased OG&A and depreciation and amortization expenses, as a percentage of sales.
Operating profit was $1.5 billion, or 2.23% of sales, for the first two quarters of 2019, compared to $1.6 billion, or 2.40% of sales, for the first two quarters of 2018. Operating profit, as a percentage of sales, decreased 17 basis points in the first two quarters of 2019, compared to the first two quarters of 2018, due to increased OG&A and depreciation and amortization expenses, as a percentage of sales, partially offset by a higher gross margin rate.