EBay Inc. may be worth $15 billion if it sells ticket unit StubHub and the classified advertising business, making an attractive acquisition target for Walmart Inc., Target Corp., Google and other companies competing with Amazon.com Inc., according to two people familiar with

Elliott Management Corp.’s thinking.

The activist investment firm of billionaire Paul Singer, which owns more than 4 percent of EBay, sent a letter to the San Jose, California-based company’s board Tuesday outlining steps it says are “urgently needed” to improve performance. Selling assets such as StubHub would reduce the acquisition cost of EBay’s core marketplace business, said the people, who asked not to be identified discussing private matters.

EBay said Tuesday it will review Elliott’s recommendations. The company’s online marketplace attracts almost 180 million customers who spend nearly $100 billion a year on the service. The classified advertising business and StubHub, which lets users buy and sell tickets to concerts and other events, combined for sales of $540 million in the quarter ended Sept. 30, about 20 percent of EBay’s revenue for the quarter.

Chief Executive Officer Devin Wenig took over the company following its split with PayPal in 2015 and made bold promises of returning the marketplace to prominence. But he’s facing increasing pressure to deliver on those pledges. EBay continues to watch Amazon grow much faster and gobble up market share and customers.