(Corrects to change sourcing to Jana Partners from company in paragraph 1) Feb 10 (Reuters) - Jana Partners is pushing TreeHouse Foods to explore options, including a sale, after taking a 7.3% stake, the hedge fund disclosed in a filing on Wednesday, sending its shares up 22%. Jana bought more than four million shares in TreeHouse as it viewed the stock to be undervalued even after nearly three years into a turnaround, the fund said. TreeHouse has a market capitalization of about $2.4 billion and its shares were trading up at $51.67 in morning trading. Jana continues to have "constructive discussions" with the board to resolve undervaluation and total stockholder return, including evaluating a sale, the filing here said. (Reporting by Aishwarya Venugopal in Bengaluru; Editing by Arun Koyyur)