MRC Global has announced first quarter 2021 results. The company's sales were $609 million for the first quarter of 2021, which was 5% higher than the fourth quarter of 2020 and 23% lower than the first quarter of 2020. Sequentially, all sectors experienced an increase in sales, except for gas utilities, which was lower due to an unseasonably higher than average fourth quarter. As compared to the first quarter of 2020, the gas utility sector sales were higher due to market share gains, and all other sectors and segments declined as the impact of the COVID-19 pandemic reduced customer spending.
Net loss attributable to common stockholders for the first quarter of 2021 was ($9) million, or ($0.11) per diluted share, as compared to the first quarter of 2020 net income of $3 million, or $0.04 per diluted share.
Rob Saltiel, MRC Global's president and chief executive officer stated, "I am pleased with the solid first quarter performance that our team delivered. Despite a slow start to the quarter resulting from customer budget resets and extreme weather conditions, we were able to achieve a 5% sequential revenue increase, a stronger bottom line and continued cash flow generation, reflecting an improved business environment.
"In my first few weeks at MRC Global, I have been very impressed with the caliber of our employees and the long-standing relationships we enjoy with our customers and suppliers. These strengths, along with our commitment to operational excellence and superior customer service, have allowed our company to become the leading PVF distributor and will support our growth ambitions in the years ahead," Saltiel added.
MRC Global's first quarter of 2021 gross profit was $103 million, or 16.9% of sales as compared to the first quarter of 2020 gross profit of $148 million, or 18.6% of sales. Gross profit for the first quarter of 2021 includes $4 million of expense in cost of sales relating to the use of the last-in, first out (LIFO) method of inventory cost accounting as compared to the first quarter of 2020, which includes income of $3 million relating to LIFO inventory cost accounting. Adjusted gross profit, which excludes the impact of LIFO, for the first quarter of 2021 was $118 million or 19.4% of revenue.
Selling, general and administrative (SG&A) expenses were $100 million, or 16.4% of sales, for the first quarter of 2021 compared to $126 million, or 15.9% of sales, for the same period in 2020. Adjusted SG&A of $98 million for the first quarter of 2021 excludes $2 million of employee separation expense.
Income tax expense was $0 for the first quarter of 2021 as compared to $5 million for the first quarter of 2020. In the first quarter of 2021, the 0% effective tax rate is a result of tax expense on foreign income offsetting U.S. tax benefits on pre-tax losses. The company's rates generally differ from the U.S. federal statutory rate of 21% as a result of state income taxes and differing foreign income tax rates.