Actual mortgage interest rates have fallen from 7.1 per cent to 4.7 per cent over the past five years, but let one bank – Westpac – increase its rate by 0.2 percentage points and the righteous indignation knows no bounds.
It may not be the end of the world, but it's certainly the end of the housing boom as we know it. Well, maybe.
But outrage is a poor substitute for understanding. Why did Westpac move? Why now? Will the other three big banks match it? And will the Reserve Bank cut the official interest rate to counteract the banks' "unofficial" increase?
Standard economic theory offers little guidance to the classic oligopolistic behaviour we get from our banks. "Game theory" is supposed to be the way economists analyse the strategic decisions of oligopolists, but I doubt it offers much help, either.
Westpac made its rate move at the same time as it joined the other big boys in announcing plans to raise more share capital. The big four are acting in expectation that the government will accept a recommendation of the Murray report that it make Australia's banking system "unquestionably strong" (that is, safe) but requiring it to hold a lot more equity (shareholders') capital.
Part of this is the intention to increase the big four's capital requirement by more than the smaller banks' increase so as put the two groups on a more equal regulatory footing. Westpac gave the cost of this requirement that it hold more capital as its justification for increasing mortgage interest rates.
It's true the requirement does increase the big banks' "cost of intermediation" – that is, the cost of borrowing from some people and lending to others, which is represented by the size of the gap between the interest rate paid to depositors and the rate charged to borrowers.
In principle, this extra cost could be passed back to depositors in the form of lower deposit rates, passed forward to borrowers in the form of higher borrowing rates, or left with the banks' shareholders in the form of lower profits. Or some combination of the three.
Obviously, bank customers would prefer that the banks and their shareholders bear the cost. And there's no reason it shouldn't happen. Our big banks have long been extraordinarily profitable – making a return on equity of 15 per cent a year – in a business that's virtually government-guaranteed.
They could easily take the hit. There's nothing sacred about 15 per cent. And in an intensely competitive banking market that's probably what would happen. In our world, however, "greedy" (read profit-maximising) banks will protect their profitability to the extent that market conditions allow.
And right now they do. It's clear Westpac's intention is to pass the higher cost on to its borrowers. Its three big competitors now must decide whether to follow suit or leave it hanging out to dry as they try to win market share from it.
Going on past behaviour, they'll follow suit. After all, a few months ago when ANZ bank raised its interest rate on investor mortgage loans by about 0.25 percentage points, the other three lost little time in doing the same. The justification was the same: the cost of the tighter capital-adequacy requirement.
But this doesn't guarantee that, this time, the others will follow Westpac immediately or by as much as 0.2 per cent – which, by the way, also applies to investor loans.
One question all this raises is whether the banks are raising rates by more than required to recoup their higher costs. The Murray report said a 0.1 or 0.15 percentage-points rise would cover it.
So, why so much, and why now? Because, at the present exceptionally low rates, the demand for home loans exceeds supply, with the banks under pressure from the authorities and sharemarket analysts to avoid lending too much – to ordinary home-buyers, not just investors.
If you have to cut back your rate of lending, why not do it by raising your prices? This suggests the housing boom may indeed be reaching its closing stages.
One reason the other banks may delay following Westpac is the talk that the Reserve will respond by cutting the official interest rate on Melbourne Cup day. They'd love to be able to hide a rate rise behind a less-than-full pass-through of a rate cut.
The Reserve may oblige, but I won't be holding my breath. Nothing in its rhetoric to date suggests it's keen to cut rather than wait. And I doubt if it would want to be seen as trying to prolong the house-price boom.
