The bank responded to a `please explain` letter from the ASX two days ago over its botched $2 billion capital raising that took place while it disclosed a rise in its impairment expense to institutional investors ahead of the wider market.

When it announced the successful completion of the initial attempted capital raising, CBA said it expected its full year 2009 impairment expense to gross loans and acceptances to be around 60 basis points.

This was higher than a November forecast of between 40 and 50 basis points.

Commonwealth Bank told the ASX in response to its `please explain` letter that it had known the new information on impairment expenses on November 16.

"The company did not consider that the information contained in the announcement with respect to the impairment expense was material to the company," CBA said in its response.

"However, the company considered it appropriate to provide this information in the context of a proposed capital raising."

CBA told the ASX the information was not material for several reasons, including the fact that it was an estimate made in the context of an uncertain economic environment.

As well, the deterioration in credit conditions, and the bank`s exposure to various distressed entities including ABC Learning, Allco Financial Group, Babcock & Brown and Centro, "is generally available information upon which analysts were able to form their own estimates of the expected full year impairment expense," CBA said.

Intersuisse director Howard Elton said the slump in the oil price had affected the market, particularly the energy stocks and major resource companies.

"The major resource stocks were pushed down.

"Rio also fell after S&P (Standard & Poor`s) downgraded their rating."

Mr Elton said Fortescue Metals was struggling again due to shipping disputes and technical mining problems. Fortescue stock declined 12 cents, or 5.08 per cent, to $2.24.

In the financial sector, Westpac gained 22 cents, or 1.38 per cent, to $16.16, Commonwealth Bank added 43 cents, or 1.62 per cent, to $26.93, National Australia Bank decreased 19 cents, or 0.96 per cent, to $19.63, and ANZ lost eleven cents, or 0.77 per cent, to $14.16.

CBA told the ASX it did not believe that information concerning its 2009 bad and doubtful debt expense was material to the company and required disclosure.

"The banks seem fairly stable today," Mr Elton said.

"People seem reassured after NAB and ANZ`s AGMs (annual general meetings) yesterday."