Shares of Wendy’s surged roughly 15% in extended trading Tuesday after a filing revealed hedge fund Trian Partners, its largest shareholder, is exploring a potential deal with the company.

Trian, along with its partners, owns a 19.4% stake in the burger chain and said it was seeking a deal to “enhance shareholder value” that could include an acquisition or merger, according to the filing.

The firm said it has retained advisors to evaluate strategic options and has discussed the scenarios with the Wendy’s board.

Wendy’s said in a statement it regularly reviews opportunities with the goal of “maximizing value for all stockholders” and would “carefully review” any proposal from Trian.

Trian, founded and run by Nelson Peltz, first invested in Wendy’s in 2005, when the fund was initially created.

“At that time, Wendy’s was one of America’s most beloved brands, but the business had lost its way after the passing of its founder Dave Thomas,” the firm says in its portfolio listing.

Trian holds three board seats at the fast-food company, including one held by Peltz , the chairman. The firm has previously urged Wendy’s to reduce restaurant overhead, improve operations and build up its brand, according to Trian.

Wendy’s and its franchisees own about 7,000 restaurants. Global same-store sales grew 2.4% in the first quarter. The company reported quarterly net income of $37.4 million, or 17 cents per share, for the three-month period ended April 3 — nearly 10% down from $41.4 million, or 18 cents per share, during the same period in 2021.

Wendy’s has experimented with new menu items and a beefed-up breakfast menu to drive traffic and compete against fast-food giants McDonald’s and Burger King. But the company faces challenging trends as diners shift their behaviors with inflation hovering at decades-high levels and some workers returning to offices.

BMO Capital Markets last month downgraded the stock to market perform from outperform and cut its price target on the stock to $22 per share from $28.

The stock closed Tuesday at $16.27 per share, down 30% over the last 12 months, giving the company a market value of about $3.5 billion.

— CNBC’s Steve Kopack contributed to this report.