Kroger shares dove Friday after the grocer's second-quarter profit slid near 8 percent as it slashed prices amid growing competition in the sector.

Kroger's stock was down 7.8 percent Friday morning.

Here's what Kroger reported compared with what Wall Street was expecting, based on a Thomson Reuters survey of analysts:

Earnings of 39 cents a share, matching expectations.

Revenue was $27.6 billion versus an estimate of $27.5 billion.

Same-store sales excluding fuel climbed 0.7 percent, better than the expected 0.4 percent growth, according to FactSet.

Although Kroger touted the work it's been doing and reaffirmed its annual forecast, investors sold off the stock, an acknowledgement that the company will be operating in a slower growth environment as Amazon uses Whole Foods to shake up the grocery business.

Kroger has taken the worst beating of any supermarket chain since Amazon announced its plans to acquire Whole Foods on June 16.

"Our second quarter results demonstrate the progress we've made," CEO Rodney McMullen said in a statement on Friday.

"We had strong growth in both loyal and total households," he added. "Traffic is up, unit movement is up, market share is up, and our customers' price perception is excellent and continues to improve."

Second-quarter net income fell to $353 million, or 39 cents per share, from $383 million, or 40 cents per share, one year ago. Excluding one-time charges, Kroger's earnings-per-share came in at 47 cents in the second quarter of 2016.

Total sales climbed 3.9 percent, to $27.60 billion.

Same-store sales, excluding Kroger's fuel centers, climbed 0.7 percent in the second quarter. This comes in 1 percentage point less than Kroger's comps during the same time a year earlier.

"We appreciate how hard it is for a company of Kroger's scale to engineer even a modest rise in same-store numbers," GlobalData Retail Managing Director Neil Saunders wrote in a note to clients.

"The principle weapon of choice has been to invest in price cuts, something that has impacted gross margins," Saunders added. "In our view, this is a necessary evil, and we believe that Kroger is right to maintain its competitiveness and dominance in the sector."

Looking ahead, Cincinnati-based Kroger has reaffirmed its outlook for the remainder of the year. But the retailer said those expectations don't include any impact from Hurricanes Harvey and Irma.

Just a day before Amazon unveiled the Whole Foods deal, Kroger cut its full-year adjusted earnings outlook to a range of $2 to $2.05 per share, down from its previous guidance of $2.21 to $2.25. The chain had cast blame on deflation in food prices and increased competition.

Kroger, meantime, expects same-store sales growth, excluding fuel, of 0.5 to 1 percent for the remainder of the fiscal year.

"As our business continues to improve, we remain committed to delivering on our guidance in 2017 and believe we have the ability to grow identical supermarket sales and market share in 2018," McMullen said.

Kroger said it will continue to provide annual forecasts, but the chain will no longer report any outlook past that, as it had been doing since 2012, citing the current "dynamic operating environment."

"We are better off giving annual guidance," Kroger CFO Michael Schlotman told CNBC's "Squawk Box" on Friday. "We don't want to make a bad decision today to try to hit something over a three-year period."

Schlotman added that Kroger feels particularly confident about its digital sales, which climbed more than 120 percent for the period. The chain has been expanding its online grocery order platform, called ClickList, boosting those results.

Kroger said it has now reduced its 2017 and 2018 planned capital investments by $600 million in an attempt to maintain its current investment-grade debt rating.

Kroger, though, will need to invest more to keep its prices low. Since the Whole Foods deal closed, Amazon has started lowering prices on produce and other items at Whole Foods' stores, promising "more to come." In turn, Kroger has suffered even more, especially with big-box retailers Target and Wal-Mart upping the ante on their own grocery offerings.

Just this week, Wal-Mart announced it has opened its 1,000th online grocery pickup location — in Amazon's backyard of Seattle. Kroger has been working with grocery delivery service Instacart to deliver items more quickly to shoppers.

As of Thursday's close, Kroger had seen its stock fall near 35 percent this year.

Kroger will hold its annual investor conference on Oct. 11 in New York.