General Mills stock took a hit Friday after the company lowered its sales estimate for the year and as investors reacted to news of the food industry's biggest takeover attempt, involving two of its rivals.

The Golden Valley-based food maker said Friday it expects net sales to drop 4 percent for the fiscal year that ends in May.

That's at the lower end of its previous guidance for a drop of between 3 percent and 4 percent. The disappointing sales numbers are primarily due to soup and yogurt. General Mills expects to deliver an adjusted operating profit margin of upward of 18 percent for the fiscal year, an increase of more than 120 basis points over last fiscal year.

The company's stock also reacted to big news over the past two days from rival Kraft Heinz. On Wednesday, that company reported lackluster quarterly results, which pressured shares across the food sector on Thursday. General Mills shares fell 2.6 percent that day.

Then, early Friday, Kraft Heinz, run by Brazilian-based 3G Capital, announced a $143 billion takeover offer for Unilever, which the London-based maker of Hellmann's, Lipton tea and Ben & Jerry's ice cream quickly rejected.

For weeks, investors have speculated Kraft Heinz would soon make another takeover offer in the food industry. Oreo-maker Mondelez International and General Mills were rumored to be the favorites. General Mills fell another 4 percent, ending at $59.23 Friday — the lowest close in nearly a year.

Erin Lash, packaged food analyst at Morningstar, forecast that Kraft Heinz would need to offer between $165 billion and $175 billion for Unilever to agree.

"Although Unilever doesn't appear to be interested, we don't believe Kraft Heinz is willing to close the book on this deal but would likely need to offer a higher price and potentially boost the cash component to bring Unilever to the table," Lash wrote in a note to investors.

A Unilever-Kraft Heinz deal would buy General Mills time to regain market momentum if 3G has made it clear that it plans to further consolidate the food industry, much like it did the global beer industry when it orchestrated the Anheuser-Busch InBev deal with SABMiller.

3G is known for its stringent accounting practices and deep cost-cutting tactics. This allows it to achieve higher than typical industry profit margins while its sales continue to drop.

General Mills has enacted its own version of zero-based budgeting, which requires each department to justify every dollar spent at the start of the year, and has closed plants and cut 5,000 jobs over the last five years.