What happened

Shares of Dollar General Corporation (NYSE:DG), a low cost retailer of products such as food, beauty aids, cleaning supplies, and other basic items, are down 8% as of 11:30 a.m. EDT Thursday after the company released weaker-than-expected first-quarter results.

So what

Dollar General reported a 9% increase in net sales, driven partially by a 2.1% increase in same-store sales. That $6.11 billion total revenue was a year-over-year improvement but still fell short of analysts' estimates calling for $6.18 billion. Diluted earnings per share checked in at $1.36 during the first quarter, which was also short of estimates calling for $1.40 per share.

A look at products down an aisle of a retail store.

Image source: Getty Images.

"Our team delivered strong net sales growth, a solid same-store sales increase, and gross margin expansion, while continuing to execute our cost containment strategy," said Todd Vasos, Dollar General's chief executive officer, in a press release. "We are proud of our execution and solid performance, particularly given the significant weather-related headwind we faced during the first quarter."

Now what

Management put part of the blame for its weaker-than-expected quarter on the weather. The company believes an unusually cold and damp season negatively impacted same-store sales in certain categories, but the truth may be that the brick-and-mortar chain is finally starting to lose some ground to e-commerce competition. That said, one quarter doesn't make a trend and investors will want to keep an eye on the company's same-store sales growth for a better idea of its business health.