NEW YORK, Oct. 14 (UPI) — Walmart saw its stock value plunge on Wall Street Wednesday after the retailer adjusted its outlook for the year and outlined billions of dollars in reinvestments that could slow growth for future earnings.

The discount retailer previously said it expected a 1 to 2 percent net growth for fiscal 2015, but said Wednesday it expects those earnings to be flatter. With the news, shares of Walmart fell by nearly 10 percent at one point in Wednesday trading — its biggest drop in more than 15 years.

Executives also indicated that future growth for the next two to three years could also be less than previously thought — maybe only 3 or 4 percent — and that earnings will drop by as much as 12 percent by January 2017.

So far this year, Walmart (NYSE: WMT) has lost nearly 30 percent of its market value — the equivalent of $79 billion.

Hoping to temper the bad news somewhat, the company announced a $20 billion share buyback program Wednesday. By midday, that was the amount Walmart had lost in market value as shares sunk to their lowest level since the 1990s.

Walmart is spending $1.2 billion this year to raise hourly wages for employees to $9 per hour, and it will spend $1.5 billion next year to hike it up to $10 per hour. The reinvestments are necessary, CEO Doug McMillon said, even though they might initially be met by lower earnings.

“We are taking decisive steps now to change and grow our business,” he said. “We can deliver stronger financial performance in the short term simply by running our core business better, but that won’t be enough.”

Walmart also plans to invest $2 billion over the next two years in its e-commerce arm, which will open online grocery operations in 20 new markets.

McMillon said Walmart — which was passed by Amazon.com this year as the world’s largest retailer by market capitalization — has a great chance to recapture that distinction.

“I like our chances,” he said, noting that it is easier for brick and mortar stores to grow their online business than it is for strictly online merchants to try and build stores.

“Retail history is very clear. Those that are unwilling or unable to change go away,” he added.

Walmart’s chief executive also said he is willing to close stores that are underperforming — which prompted speculation by some analysts that company assets, like Sam’s Club, could possibly be sold off.

Walmart, which notched net sales of $482 billion last year, said it expects those figures to rise by between $45 billion and $60 billion over the next three years.