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Fastenal (FAST - Get Report) shares were down Thursday after the industrial- and construction-supplies distributor reported disappointing earnings, a possible new sign of weakness in the manufacturing sector.

Higher tariffs on goods produced in China and then imported to the U.S. were a key factor in Fastenal's lower-than-expected earnings, the company said in a statement.

The shares were trading off 4.7% to $29.77 after the Winona, Minn., company posted second-quarter earnings of 36 cents a share, a penny lower than the estimate of analysts surveyed by FactSet.

Fastenal's $1.37 billion of revenue was up from $1.27 billion a year earlier but short of analyst expectations of $1.38 billion.

The company's statements are considered a potential barometer for the health of the manufacturing sector. It had beaten revenue estimates three of the past four quarters.

The higher tariffs combined with "general inflation in the marketplace" cut into its profit margins, Fastenal said.

"While we successfully raised prices as one element of our strategy to offset tariffs placed to date on products sourced from China, those increases were not sufficient to also counter" inflation, the company said.

Overall, gross profit as a percentage of sales has decelerated this year, falling 1.8 percentage points from the first quarter to 46.9% in the second quarter, the company reported.