With only a week and a bit before Commonwealth Bank delivers its December half profit – and kicks off the February reporting season proper – it’s time to play the Australian market’s favourite game: how to justify CBA’s valuation, which is the highest in the history of developed market banking.

There are plenty of interesting threads to this debate, from the role that passive and superannuation fund flows have played in the last 12 months, to the state of mortgage market competition (which is starting to heat up again, according to Macquarie) and the battle for banking deposits and loans.