Increasing industrial production and manufacturing growth, especially from heavy-equipment makers, led to a nearly 15 percent increase in sales for Fastenal in its fourth quarter.

Sales for the Winona-based distributor of industrial parts and equipment rose to $1.1 billion for the quarter and rose 10.8 percent for the year to $4.4 billion.

Earnings were $152.4 million, or 53 cents per share, up 33 percent from the same period the year before. Earnings adjusted for discrete tax items were 45 cents per share, which matched expectations of analysts polled by Thomson Reuters.

“A return to double-digit sales and pretax earnings growth in 2017 was a great way to celebrate our 50th year in business,” said Dan Florness, president and CEO, of the company’s earnings release.

Despite the strong sales and earnings, Fastenal shares closed at $52.20, down 6 percent, as the company reported lower gross profit as a percentage of sales, as a result of higher employee-related expenses.

Fastenal’s gross profit, as a percentage of net sales, declined to 48.8 percent in the fourth quarter from the 49.8 percent the year before. And the company’s operating income as a percentage of net sales declined to 18.7 percent, down from the 19.3 percent reported in the same quarter last year.

Total employment at Fastenal increased to 17,519, a 7.7 percent year-over-year increase. That contributed to a 15.5 percent increase in employee-related expenses, including bonuses, commissions and profit-sharing, compared to the fourth quarter of 2016.

Transportation expenses also contributed to the company’s increase in operating expenses. Selling transportation expenses increased 7.4 percent due to higher fuel expenses and Fastenal’s investment in its hub-fleet capabilities.

Fastenal sells through its retail stores, industrial vending machines and Onsite locations within customer locations. Its sales base continues to grow despite the closure of 37 traditional stores. The number of installed industrial vending machines is now 71,421 machines, a 13.7 percent increase over the fourth quarter of 2016. The company also signed 57 new Onsite locations during the quarter compared to 43 signings in the fourth quarter of 2016.

Shares of Fastenal are up 11 percent in the last year. Shares have traded in a range of $39.79 to $56.15 per share over the last 52 weeks.