The Commonwealth Bank's quarterly market update, released last week, contained the usual dense set of financial disclosures. Three numbers matter, and are worth pulling out.

First: 90-day arrears on the mortgage book have ticked up from 0.66 per cent to 0.79 per cent since November. That is still a low absolute number, but the direction is what analysts will focus on. Second: the proportion of mortgages that were originally underwritten at floor rates below the current cash rate. That share has fallen, as fixed-rate rollovers work through the book. Third: the provisioning charge for the quarter, up modestly year-on-year but not remarkable.

What it adds up to

The bank's mortgage book is, at the aggregate level, still performing. Individual borrower stress, particularly in outer suburbs of Sydney and Melbourne, is real and rising. Neither observation contradicts the other. Both matter for how the RBA thinks about the transmission of monetary policy through the household sector.