After a couple of terrible trading sessions, Australia's big four banks are rebounding on Friday despite the market weakness. The best performer in the group has been the Australia and New Zealand Banking Group Ltd ( ASX: ANZ ) share price with a 1.5% gain. Investors appear to believe the big four banks have been oversold since the Reserve Bank lifted the cash rate on Tuesday. A note today reveals that analysts at Macquarie have have suggested the recent bank selloff is a buying opportunity.