For years for Americans, buying yogurt meant buying Yoplait or Dannon.

That all changed in 2007 when a tiny company called Chobani entered the market with a new, old product: Greek yogurt. Instead of a snack or side item at breakfast, the higher protein levels in Greek yogurt made it a worthy meal. Chobani quickly grew while the incumbent yogurt giants, skeptical of the new product's staying power, were slow to react.

Yoplait's maker, General Mills, was exceptionally slow.

The Golden Valley-based packaged foods giant went from 30 percent of the yogurt segment five years ago to about 20 percent as of May, with the last 10 months seeing sharp declines, according to Nielsen data provided in a Bernstein Research report.

Executives acknowledged the difficulties of its yogurt business at its last earnings call in March. With the company set to release its year-end results for the 2016 fiscal year on Wednesday, investors are looking for signs that the worst is behind for Yoplait.

"General Mills is a vaunted marketer of foods," said David Palmer, an analyst with RBC Capital Markets. "We want them to fix this. That's their job."

At 13 percent of company sales, yogurt is General Mills' second-largest business behind cereal. The business peaked in 2010 at just over $1.5 billion in revenue. It dropped to $1.3 billion in fiscal 2014, then climbed to $1.4 billion last year. But its yogurt sales fell again last fall, and investors this week will learn how the company finished the full fiscal 2016.

General Mills declined to discuss yogurt this close to its year-end earnings report. Jeff Harmening, General Mills' COO of U.S. Retail and incoming president, said in March on its third-quarter earnings call that dairy costs, which are at a 20-year low, have created opportunities for new brands and allowed its competitors to make greater investments. Competitors are spending heavily on advertising and on deals with retailers to get shelf space for their product.

"Yogurt is an attractive growth category now and for the long term," Harmening said in March. "Over time, innovation and great marketing will be the key factors to winning in this category."

Analysts say General Mills' biggest misstep was failing to see how disruptive Greek would be. Consumers, motivated by the perception of health, flocked to the dense, slightly sour product. Greek skyrocketed from 1 percent of all U.S. yogurt sales in 2007 to more than 50 percent last year.

"They underestimated Greek from the start," Palmer said. "General Mills may have been tempted into thinking this was a fad because taste and price usually win."

Its largest rival Dannon, the U.S. arm of French yogurt maker Danone, was able to salvage its 35-plus percent market share throughout the last five years thanks to the early and successful launch of Dannon Oikos — its Greek yogurt product with a Greek name.

General Mills' initial launch of Yoplait Greek was a flop. It reformulated the product in 2013, using a more traditional "straining" method that builds the rich, thick profile. That same year it also released the industry's first 100-calorie Greek yogurt, Greek 100, which became General Mills' biggest-selling new Yoplait product in more than 20 years.

Today, sales are rising for Yoplait Plenti, its Greek yogurt product that's mixed with fruit, oats, flax and pumpkin seeds, and from Annie's Homegrown yogurt, a well-known organic brand General Mills acquired in 2014. This supports General Mills' acquisitions strategy of capturing consumers — like millennial moms — who are increasingly migrating toward natural and organic brands.

General Mills began making venture investments last fall through 301 Inc., a product development unit it ­created in 2012 that's named after the address of an old Pillsbury flour mill in Minneapolis. The unit originally was focused on innovation for products outside General Mills' well-established wheelhouse, but it pivoted strategy last fall and now seeks fledgling, independent food companies that need some help. 301 offers young companies an infusion of capital and access to General Mills' massive expertise, and a successful venture target could spell a direct path to acquisition by General Mills.

Last month, 301 Inc. made its largest investment yet when it gave $18 million to a ­northern California maker of vegan yogurt and cheese.

The company also said in March that it will have news in the organic yogurt market this summer.

"Following the rise of Greek yogurt, General Mills management has said they are working to stay on top of consumer trends to ensure they can avoid having a similar misstep going forward," said Erin Lash, a food analyst at Morningstar Inc. "From the outside, that's hard to see, but they've said that's their intention."

Kristen Leigh Painter • 612-673-4767