The private equity-backed company, which makes the helmets of most National Football League players, said it had engaged investment banks UBS Group and Robert W. Baird & Co to explore market interest.

"The execution by Riddell's industry-leading team, unprecedented growth fueled by innovation, and other positive developments make the company a desirable acquisition target," Riddell said in a statement.

Private equity firm Fenway Partners has owned Riddell for the last two decades. Other buyout firms have shown interest in the company, which generates around $85 million of annual earnings before interest, taxes, depreciation and amortization (EBITDA), the sources said.

Riddell was founded in 1929 by John T. Riddell who invented gear such as removable football cleats and plastic helmet shells.

Fenway Partners acquired Riddell Sports Group in 2003 and combined it with Bell Sports in 2004. In 2006, it merged it with Easton Sports in a transaction valued at approximately $400 million and renamed it Easton-Bell.

In 2014, Fenway again changed the company's name to BRG Sports for its core Bell, Riddell and Giro brands and sold its Easton baseball and softball business to Bauer Performance Sports. In 2016, Vista Outdoor, manufacturer of sporting and outdoor products, acquired the Bell, Giro, Blackburn and C-Preme brands from BRG Sports, leaving Riddell as its remaining brand.

Last week, Marucci Sports, another sports equipment company that makes baseball gear, was acquired by Fox Factory Holding Corp for $572 million, 10.5 times its last 12 months' EBITDA of $54 million.

While a similar multiple would imply a valuation of around $800 million for Riddell, some of the sources said that negative press coverage of the concussions that NFL players suffer could weigh on the deal value.

(Reporting by Abigail Summerville in New York; Editing by Rod Nickel)

By Abigail Summerville