Shareholders in Halifax Bank of Scotland are due to vote on plans for a £4 billion cash injection.
The high street giant, which is Britain's biggest mortgage lender, is asking investors for the mammoth sum to help bolster its balance sheet.
Like the UK's other major banking groups, HBOS has suffered multi-billion pound investment write downs as a result of the credit crunch.
The group's cash injection has been proposed through a rights issue, in which new shares are sold to investors at a discounted price of 275p to make them tempting for investors.
HBOS shareholders will gather in Edinburgh to discuss and vote on the scheme. The bank has some two million smaller investors, owning around 27% of the capital.
While the rights issue is likely to get shareholder approval, their appetite for the new shares could be dented by the bank's fluctuating share price.
Recent fears over the banking sector's health have seen HBOS's stock dip below the rights issue price in recent weeks, making it cheaper for shareholders to go onto the open market to buy shares rather than through the "discounted" rights issue.
Earlier this month the price hit 258p, forcing the bank to issue a statement insisting that the cash call remained on track.
This month has also seen HBOS warn house prices could fall 9% this year and its bad debts rise as more borrowers struggle with repayments.
Any new shares not taken up by existing shareholders during the rights issue will be bought by the scheme's underwriters, Dresdner Bank and Morgan Stanley.
