Kroger's winning streak has come to an end.
The supermarket chain's same-store sales, or sales at stores open at least a year, fell 0.7% in the most recent quarter, the company said last week.
That marks the end to a staggering 13-year streak of quarterly same-store sales increases for Kroger.
The company blamed food price deflation for the decline.
But it's also facing growing price competition with discount grocers like Aldi expanding across the US.
A 2014 price study found that Aldi's prices were about 22% cheaper than Kroger's. Aldi has more than 1,600 stores in the US with plans to open another 600 within the next couple of years.
Walmart is also investing in its grocery department. The company reduced prices on hundreds of grocery products last year and reportedly just launched a grocery price-comparison test in 1,200 stores in an effort to edge out Aldi.
Business Insider compared prices at both chains in 2015 and found that Walmart was about 30% more expensive than Aldi.
Business Insider/Hayley PetersonSoon, there will be even more pressure to lower grocery prices with a new discount grocer entering the US market in a big way.
The German supermarket chain Lidl is gearing up to open 100 stores along the East Coast by mid-2018, with the first 20 stores opening this summer in Virginia, North Carolina, and South Carolina.
The chain plans to eventually open as many as 600 stores in the US, according to a copy of a company presentation obtained by Business Insider. Lidl currently has 10,000 stores in 27 European countries.
The rapid expansion of Aldi and Lidl in the UK has sent the country's biggest grocery chains into a crippling price war that sent their sales sliding over the last decade.
The end to Kroger's 13-year winning streak is a sign that a similar price war is erupting in the US. Fortunately for shoppers, that means food will just keep getting cheaper.