Westpac's steady margin leans on the line it controls least

Which line produced the margin?

In the composition Westpac disclosed, the net interest margin ran at 1.94 per cent, 1.84 per cent and 1.89 per cent across three quarters. Over the same period the core margin from lending and deposits went 1.79 per cent, 1.77 per cent and 1.78 per cent, while the treasury and markets contribution moved through 15, 7 and 11 basis points. Average interest-earning assets rose from 1,029 billion to 1,056 billion.^[1]

These lines reduce to one piece of arithmetic. The treasury and markets contribution went from 7 basis points to 11 basis points while the core margin advanced only from 1.77 per cent to 1.78 per cent, and that is what carried the headline margin from 1.84 per cent to 1.89 per cent. Most of the recovery came from the trading side rather than from pricing power in the lending book. A reasonable alternative reading exists: the treasury contribution can persist to the extent that the balance-sheet and hedging position is structural, and the 15 basis points of the first quarter supports that. What settles it is whether the line holds 11 basis points next quarter.^[1]

What the lending side says

Westpac reported that average monthly mortgage applications between 15 May and 31 July came to 26,000, down 20 per cent on the March quarter, after the bank had earlier flagged a decline of 11 per cent following federal budget changes. Its own economists forecast total housing credit growth easing from 6.8 per cent in 2026 to 4.7 per cent in 2027, with investor credit falling from 9.1 per cent to 4.5 per cent.^[1]

Lending grew 2 per cent and deposits grew 2 per cent in the quarter, and that growth carries the volume leg of the margin. If application flow stays at the post-budget level, this volume line is the model's most fragile assumption: even a bank that defends price has a smaller book to grow. The second indicator on the same page points the same way, because it is the bank's own economists who expect housing credit growth to slow.^[1]

Where capital and provisions stand

The common equity tier one ratio fell from 12.4 per cent at the end of March to 12.1 per cent at the end of June. The bank said the sale of the RAMS mortgage portfolio, completed on 1 August, added 23 basis points to the ratio, while the share buyback took 22 basis points out. On provisions, collectively assessed cover fell 2 basis points to 1.27 per cent of credit risk-weighted assets, stressed exposures rose 3 basis points to 1.19 per cent, and total provisions to gross loans held at 58 basis points.^[1]

That mix also names the indicator to watch. If application flow stays at the post-budget level, the direction of the core margin rather than the headline margin will decide how to read the 2026 full-year result: should the headline margin rise while the core margin stays at or below 1.78 per cent, the gain will again have come from the trading side. One line is enough to tell them apart, because the bank publishes the composition quarter by quarter.^[1]