I think the banks sold off as AUS recorded its first qtr of deflation since 2008, giving rise to the possibility (likelihood) of RBA rate cut, which negatively impacted the banks. The AUD plunged for the same reason, prospective lower rates. It seems to be holding steady now, limping marginally upwards after calamitous decline(see chart).
I started a thread on the CPI Release after the ABS released the numbers, about noon today Post 17608055
