Sullivan said West Ham would be worth £400 million when they move to London's Olympic Stadium in 2016.
"We've no desire to give up the whole club but we're still £110 million in debt - albeit now £55 million of that is to ourselves," said Sullivan. "So the third-party debt has been halved but only because we put the money in."
Sullivan bought West Ham with co-chairman David Gold in 2010 when the club was valued at £105 million.
"We lost £30 million when we went down (to the Championship in 2011) and we made 10 million on paper last year," he added.
"I'd love someone to come in and pay 20% and the money would not go to us, it would go to the club.
“The move to the Olympic Stadium should cover most of the debt but if it doesn't happen we'll dig into our pockets and keep the club afloat."
West Ham are riding high in fifth place in the Premier League and Sullivan admitted that manager Sam Allardyce could leave Upton Park at the end of the season when his contract expires.
West Ham brought in nine players before this season, including strikers Enner Valencia and Diafra Sakho, and midfielder Alex Song.
Sakho, who has scored seven league goals, was signed on the recommendation of West Ham vice-chairman Karren Brady's brother and Sullivan said Allardyce had been against the move.
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