The level of borrowing of HBOS stock, a key measure of short-selling, has been lower since the bank began a £4bn rights issue than it was beforehand, undermining claims by bankers and regulators that the shares were attacked by hedge funds.

The Financial Services Authority introduced surprise new rules last week demanding disclosure of significant short-selling - bets that shares will fall - during rights issues, and said it was "as certain as certain can be" that sellers were abusing the market.