If a manager has -ve balance before placing the INITIAL bid, it will be rejected.

But if he starts on a positive balance e.g. $10M, he can bid on multiple players worth under $10M, as long as all the bids are still active.

If he bids 5 $5M players while having a balance of $10M and wins 3, he'll be at -$5M.

Furthermore, once you have your initial bid locked in, you can't add bids for that player with -ve balance, the bid will not be accepted.

Hope that explains.

If you meant that he put his initial bid WHILE having a -ve balance, then this is a technical issue.