SPRINGFIELD, Mo. (AP) -- O'Reilly Automotive Inc. said Wednesday its third-quarter profit more than doubled as sales rose and it gained greater purchasing power as the result of acquisitions.

The auto parts retailer, based in Springfield, Mo., earned $87.2 million, or 63 cents per share, in the quarter that ended Sept. 30. That is up from the $41.4 million, or 31 cents per share, it earned a year earlier.

Revenue grew 13 percent in the quarter to $1.26 billion from $1.11 billion. Sales at stores open at least a year rose 5.3 percent, O'Reilly said, as more people chose to repair existing cars rather than purchase new ones.

The results beat a 56-cent-per-share profit estimate from analysts polled by Thomson Reuters and their forecast for $1.23 billion in sales.

The company said there was continued improvement in its gross margin thanks to an increase in purchasing power that lowered its acquisition costs.

O'Reilly forecast fourth-quarter profit of 47 cents to 51 cents per share and full-year earnings of $2.18 to $2.22. On average, analysts are predicting earnings of 47 cents and $2.13 per share for the respective periods.

Shares fell 7 cents to $33.61 in aftermarket trading after closing Wednesday down nearly 3 percent at $33.68.