West Ham's obligation to sign on-loan Nice defender Jean-Clair Todibo on a permanent basis has been activated after the club retained their Premier League status.
The France centre-back joined the Hammers on a season-long loan from the Ligue 1 side last summer, and the deal included a potential obligation to sign him full-time.
The conditions of the transfer have remained confidential, but multiple sources have told BBC Sport the primary stipulation in West Ham's agreement with Nice over a permanent deal was retaining their Premier League status.
That was confirmed on Saturday when Ipswich became the final club to have their relegation into the Championship confirmed.