August saw National Australia Bank Ltd (ASX: NAB), ANZ Group Holdings Ltd (ASX: ANZ), Westpac Banking Corp (ASX: WBC), and Commonwealth Bank of Australia (ASX: CBA) shares all come under pressure.
Indeed, amid a deteriorating outlook for the Aussie economy and housing market, all of the big four S&P/ASX 200 Index (ASX: XJO) bank stocks underperformed the 1.1% gains posted by the ASX 200 in the month just past.
Here's how they stacked up.
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CBA shares trail the pack
CBA shares tumbled 9.9% in August, closing the month trading for $159.90 apiece.
Though we should note that CBA stock traded ex-dividend on 19 August. If we add the final fully-franked dividend of $2.70 a share back in, then the accumulated value of Australia's biggest bank stock declined by a lesser 8.4%.
CommBank reported its full-year FY 2026 results on 12 August.
CBA achieved a 6.2% year-on-year increase in operating income to $30.2 billion. And the bank's cash net profit after tax (NPAT) of $11.0 billion was up 7%.
But investors appeared concerned over the outlook, with management noting that household spending is softening while it expects Australia's economic growth to slow.
CBA shares closed down 0.7% on the day of the results release.
Westpac shares tumble on quarterly update
Westpac shares also just finished a month to forget, tumbling 8.8% to close out August trading for $34.55 apiece.
Westpac released its third-quarter update on 10 August.
Positively, the ASX 200 bank stock reported a 1% year-on-year increase in operating income to $5.7 billion, with the net interest margin (NIM) remaining steady at 1.89%.
On the bottom line, Westpac achieved a quarterly statutory net profit of $1.8 billion, up 3% from the prior quarter.
However, investors will also have noted the bank's expectations of moderated lending growth in the months ahead.
And the bank could be facing higher non-performing loans.
According to management:
Credit impairment provisions were $5.3 billion as at 30 June 2026, with provisions above expected losses of the base case economic scenario increasing to $2.0 billion.
Like CBA shares, Westpac shares came under pressure following the update, closing the day down 5.9%.
NAB shares fall on lower home loans
NAB shares didn't escape the selling pain in August either, closing the month down 6.5% to trade for $38.63 each.
NAB shares closed down 4.6% on 17 August following the release of the bank's own third-quarter results.
Highlights from the quarter included cash earnings of $1.83 billion, up 2% from the first-half quarterly average (excluding large notable items). And NAB achieved a 32% increase in net profit to $1.81 billion.
But investors were favouring their sell buttons with management flagging a decline in the bank's crucial home lending market.
"The Australian home lending market softened in 3Q26 with our applications down 15% compared with 2Q26," NAB CEO Andrew Irvine said.
ANZ shares lead the pack
Outperforming NAB, Westpac, and CBA shares in August, though still edging lower, we find ANZ.
ANZ shares closed on 31 August trading for $37.20, down 0.3% over the month.
Unlike the other three big bank stocks, ANZ shares closed up 4.5% on 13 August following the release of the company's third-quarter update.
While revenue was flat for the quarter, ANZ reported a cash profit of $1.90 billion, up 1% on the quarterly average for the half year ended 31 March.
And investors were favouring their sell buttons, despite ANZ noting a 12% drop in mortgage applications since the Federal Budget's changes to property taxes.
