Senior management and staff at HBOS have bought more than £6m worth of the bank's shares after a steep fall in the firm's share price last week.
HBOS owns Halifax and Bank of Scotland
The bank said the move was a "demonstration of confidence" after it was hit by "malicious rumours".
HBOS boss Andy Hornby spent £414,000 of his annual bonus to buy 92,812 shares.
He was joined by bank's executive directors and 250 senior managers, who together purchased 1.4 million shares at 446.25p.
Last Wednesday, HBOS shares at one point fell as much as 17% amid rumours it was facing similar problems to Northern Rock.
HBOS said the rumours were ill-founded and malicious.
The UK's financial watchdog, the FSA, is investigating whether the rumours had been deliberately spread to undermine the value of bank shares.
Shares in HBOS ended the week at 473.50p.
Referring to the purchases, an HBOS spokesman said: "This is a very straight forward demonstration of the very high confidence our senior management has in HBOS.
"This is a very strong company with good prospects."
They added: "This sort of thing is exactly what the City wants to see, and this is the best answer to those people who spread false and malicious