The company also revealed it had agreed to buy 18 convenience stores operating under the Texas Star brand from Texas Star Investments Inc. and its affiliates.
Shares dropped 1.8% to $60.12 at 12:35 p.m. in Toronto, paring this year’s rally to 23%.
The Laval, Quebec-based company said its CFO resigned to "pursue other interests and spend more time with his family."
Raymond Pare has been with the Couche-Tard for 13 years, including about seven as CFO.
Chief executive Bran Hannasch will take care of financial and investor issues until a replacement is found.
The purchase also includes two Subway stores and a dealer fuel supply network in the southern part of Texas.
The price of the deal was not disclosed.
The convenience stores will be converted to the Circle K brand and will continue to sell Shell and CITGO-branded fuel.
With this deal, Couche-Tard’s U.S. Southwest division will include 513 corporate and franchised stores.
As of July 19, Couche-Tard's network comprised 7,987 convenience stores throughout North America, including 6,556 stores offering road transportation fuel.
The deal is expected to close by next April.