Mondelez International stock gained early Thursday, after news that activist investor Bill Ackman has taken a $5.5 billion stake in snack maker and is considering pushing for a takeover of the company.
Ackman's $20 billion fund, Pershing Square Capital Management, disclosed a 7.5 percent stake in Mondelez late Wednesday. Illinois-based Mondelez is a heavyweight among global packaged food makers with brands like Ritz and Cadbury.
In premarket trading Thursday, the stock was up more than 5 percent. (Click here for the latest price.)
Sources familiar with Ackman's thinking told CNBC that private equity firm 3G Capital, through its ownership of Kraft Heinz, would be the most likely buyer should Ackman push Mondelez to pursue an acquisition. However, there has been no indication that Ackman has reached out to 3G.
The view is that Mondelez has meaningfully lower margins than 3G has been able to produce at Heinz and what the market expects the firm to be able to achieve with Kraft.
In 2012, Mondelez spun off its grocery business into Kraft Foods Group, which merged with ketchup maker H.J. Heinz earlier this year to form Kraft Heinz. Kraft Heinz is backed by Warren Buffett's Berkshire Hathaway and 3G.
It is unlikely that Kraft Heinz would be able to do a deal of this scale in the next 18 months to two years because it only recently completed its merger and still has fairly high debt, said Alexia Howard, Sanford Bernstein & Co. senior food research analyst.
"It might be a little difficult to get something to happen in the very near term. And the question is, over that next 18 months, can Mondelez deliver performance to such a degree that they get out ahead of where Kraft Heinz might be willing to go after them?" she told CNBC's "Squawk Box" on Thursday.
Mondelez has already begun to improve profit margins over the last 18 months, and that progress has accelerated recently, Howard said. She sees further room for improvement as the company lowers plant costs, reduces its headcount and narrows its product range.
Ackman believes Mondelez is a great business with products in the right areas, no private label competition and a significant presence in emerging markets, sources told CNBC.
Pershing Square said its beneficial ownership of 120.3 million shares includes forward purchase contracts and call options. Ackman's stake is valued at about $5.5 billion based on Mondelez's closing price on the Nasdaq on Wednesday.
Pershing Square began buying Mondelez shares at the end of March.
"We welcome Pershing Square as investors in our company," a Mondelez spokeswoman said. "We'll continue to focus on executing our strategy and on delivering value for all our shareholders."
With Ackman's disclosure, Mondelez now has two of the best known activist investors as significant shareholders. Nelson Peltz's Trian Fund Management LP holds a 3 percent stake in Mondelez, according to Thomson Reuters data.
Peltz told CNBC he is pleased that Ackman sees the value in Mondelez that Trian does.
Peltz, who is on Mondelez's board, played a role in the breakup of Kraft into Kraft Foods Group and Mondelez. Peltz said in April that he was not pushing Mondelez to do a big deal and wanted the company to continue improving its profit margin, sales and market share.
The Wall Street Journal, which revealed the deal, reported that Ackman was betting the firm would soon merge with another food giant. Should that transpire, it would create significant aftershocks for the U.S. food sector and mark the latest development in a wave of industry-wide consolidation, the Journal said.
—Reuters contributed to this report.