The FBI is warning sports leagues that star athletes who display valuables on social media are vulnerable to burglars familiar with their often-public travel schedules.

The bureau recently issued the best-practices memo as part of a long-standing practice of communicating with private businesses about crime trends, a U.S. official briefed on the matter said.

The memo, a “liaison information report,” urges the leagues to advise athletes to limit imagery of valuables, such as cash, jewels and…