Commonwealth Bank shares suffered their worst single-day sell-off since the depths of the March 2020 COVID-19 correction on Wednesday, as investors fretted about the squeeze on profits caused by the record low cash rate and fierce home loan competition.

Australia’s biggest bank said its net interest margin was “considerably lower” over the quarter as it battled headwinds such as low yielding cash and bonds, sharp home loan pricing and a higher proportion of low fixed rate loans on its books.