Manchester City would be interested in signing Raheem Sterling if he were to become available, according to Sky sources.
Tottenham have completed a deal for Cologne defender Kevin Wimmer and he will join them in June, Sky sources understand.
Sky Bet Championship side Bolton announced on Monday they had signed the 22-year-old on a deal until January.
But Cardiff boss Malky Mackay then decided Mason should stay with the Barclays Premier League club and informed Wanderers counterpart Dougie Freedman later that evening.
A statement on Bolton's official website on Tuesday afternoon read: "Joe Mason will remain with Cardiff City following talks between Dougie Freedman and Cardiff boss Malky Mackay yesterday (Monday) evening.
"It was at the Cardiff manager's request that the striker remained in South Wales."