The NBA has opened an investigation into a possible tampering violation committed by the Philadelphia 76ers centered on their signings of James Harden, P.J. Tucker and Danuel House.

Harden declined his $47 million player option to sign a one-plus-one contract with the 76ers at $33 million in Year 1 to give the team flexibility to sign Tucker and House.

Some have wondered if another deal with Harden is in place for the future, which would be a violation of league rules.

Tucker joined the Sixers from the Miami Heat on a three-year, $33.2 million deal.