Sept 22 (Reuters) - Jana Partners on Thursday disclosed a 9.6% stake in Freshpet Inc and said it could push the pet food maker to evaluate a sale of its business, indicating another round of corporate activism in the retail industry by the hedge fund.

The New York-based investor said in a regulatory filing that Freshpet's shares, down nearly 60% so far this year, are undervalued.

Jana Partners has a history of pushing for change in the food and beverage industry. It had previously urged for changes at Whole Foods that was later sold to Amazon, and at Pinnacle Foods, which Conagra Brands acquired in a nearly $11 billion deal in 2018.

Jana Partners has also been pushing for changes at packaged food maker TreeHouse Foods Inc since last year. In April, TreeHouse said it had appointed Scott Ostfeld, a partner at Jana, to its board as part of an agreement with the New York-based company.

Freshpet has not yet spoken to Jana, but will "look forward to hearing their perspectives", the company said in an emailed statement.

In its second quarter, Secaucus, New Jersey-based Freshpet reported a 34% jump in revenue to $146 million. But higher expenses due to inflationary pressures and supply chain snags led to a bigger loss in the quarter.

The news of Jana's stake was first reported by the Wall Street Journal. (Reporting by Niket Nishant and Ananya Mariam Rajesh in Bengaluru; Editing by Shinjini Ganguli and Maju Samuel)