Aussie shares log fourth session of losses, banks drag

The local share market fell for a fourth session as investors mull a tax shake-up. (Lukas Coch/AAP PHOTOS)

Australian shares have fallen for a fourth straight session, as CommBank led the big banks lower, eclipsing a broadly positive session elsewhere.

The S&P/ASX200 fell 40.3 points on Wednesday, down 0.46 per cent, to 8,630.4, as the broader All Ordinaries lost 28.9 points, or 0.32 per cent, to 8,880.7.