Barnes & Noble is weighing a potential sale of the chain after receiving interest from “multiple parties,” including one led by Chairman Leonard Riggio, who owns 19.2 percent of the company.

Its board appointed a special committee to review the offers and Riggio agreed to vote his shares in support of the committee’s decision.

At the same time, the board adopted a shareholder rights plan, which will expire on Oct. 2, 2019. The plan will be triggered if a person or group acquires more than 20 percent the chain’s common stock. Investor Richard Schottenfeld in recent months has built a 6.9 percent stake in the business.

Barnes & Noble has struggled to compete with online retailers and several attempts to revamp its stores have failed to gain traction. It also has had five chief executive officers since 2013, including Demos Parneros, who left the company in July after talks failed on a potential sale of the chain.