Activist investor Jana Partners disclosed a 9.1 percent stake in Pinnacle Foods on Thursday and said it would seek talks with the company on a range of subjects including a possible sale of the packaged foods maker.
Jana, in a regulatory filing, also said it would have talks with Pinnacle about the composition of its board of directors.
"We are aware that Jana Partners has made a 13D filing regarding its investment in Pinnacle Foods," a company spokesperson said in an email to Reuters.
"Pinnacle's Board of Directors and management team welcome stockholder input and are committed to continuing to create value for all stockholders."
Its shares rose nearly 8 percent to $59.75 in after-hours trading on Thursday.
Investors have circled Pinnacle for some time, and some investors had hoped for a merger. But talks between the company, which makes Duncan Hines bake mixes and Vlasic pickles, and ConAgra Brands, which sells Peter Pan peanut butter and Pam non-stick cooking spray, broke down.
Some investors have said privately earlier this year they would like Pinnacle to revisit a possible merger and said that Conagra could still be a potential suitor.
Jana is known on Wall Street as a one of the industry's most respected activist investors often preferring to work away from the limelight and steering clear of proxy contests that many celebrity activists embrace.
Earlier this year, Bloomin' Brands, which owns Outback Steakhouse and Bonefish Grill, added a new independent director amid prodding from Jana.
One year ago, Jana took a stake in Whole Foods Market and vowed to shake up the board to help improve the grocer's under-performance. But the company sold itself to Amazon instead.