GOODLETTSVILLE (AP) — Dollar General CEO Rick Dreiling plans to retire from that post next year.

The company's shares fell more than 4 percent in morning trading after the announcement on Friday.

The discount store operator said that the retirement is effective on May 30, 2015, or when a successor is appointed. The 60-year-old Dreiling — who also serves as chairman — has agreed to remain as chairman during the transition process once a new CEO is named.

Dreiling has served as Dollar General's CEO since January 2008. He became chairman in December of that year.

The company said that its annual sales have surged more than 80 percent to $17.5 billion during Dreiling's tenure. Its store count has climbed 38 percent to more than 11,000 stores in 40 states during that time.

Dollar General Corp., based in Goodlettsville, Tennessee, is currently conducting a search for a new CEO.

Earlier this month the company reported a slight rise in its fiscal first-quarter profit as sales improved.

Its shares dropped $2.79, or 4.5 percent, to $58.89 in morning trading. Its shares had been up 2.2 percent so far this year through Thursday's close.