ASX bank shares are heading into one of the most important weeks of the year.
The Reserve Bank of Australia hands down its next decision at 2:30pm on 11 August, and the day after that, Commonwealth Bank of Australia (ASX: CBA) opens the sector's full-year results season.
Westpac Banking Corp (ASX: WBC), National Australia Bank Ltd (ASX: NAB) and ANZ Group Holdings Ltd (ASX: ANZ) all run September year ends, which makes the RBA call the first real catalyst for ASX bank shares of the period.
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What the RBA decision could mean for ASX bank shares
The cash rate currently sits at 4.35%, following three increases through 2026 that not many people were forecasting a year ago.
In its latest move, the Reserve Bank left the rate on hold in June while it assessed the response to those earlier rises. Most economists expect the same again.
CommBank's own economics team expects the cash rate to remain at 4.35% through 2026 and does not forecast cuts until 2027.
A hold would be the path of least resistance for the sector. It removes near-term uncertainty without adding fresh pressure to household budgets, which is exactly what a lender wants heading into results.
There is also a second date worth marking beyond the RBA meeting itself.
CBA will release its FY26 result and final dividend on 12 August, with the shares scheduled to trade ex-dividend on 19 August and payment due on or about 29 September.
Why higher rates don't automatically help ASX bank shares
There is a common assumption that rate rises are unambiguously good for the banks.
The reality is messier. Higher rates do lift the return banks earn on deposits they hold at low or zero interest.
But savers respond by shifting money into term deposits and high-interest accounts, and that behaviour claws back much of the initial benefit.
The margin data from the latest half-year results bears this out. NAB's net interest margin rose three basis points to 1.81% over the half, whilst Westpac's fell three basis points to 1.89% on the same basis.
ANZ reported a group margin of 1.53% across the half. Management has flagged a bias to the upside in margins (excluding Markets) next period.
The bigger risk is as follows.
Westpac carries the heaviest mortgage exposure of the four, with roughly 69% of its loan book in residential lending.
Higher rates eventually feed through to arrears, and the full effect of this year's tightening has not yet arrived.
What brokers are saying
Analysts are unusually divided on the sector right now.
Morgan Stanley holds sell ratings on CBA, NAB and Westpac shares, and its CBA target of $125 implied around 26% downside when the note landed in July.
Jefferies is similarly cautious, with a sell rating and a $144.40 target on the same stock.
Broader consensus data has also shown sell or hold ratings dominating across the majors for much of the year.
Not everyone is bearish, though.
Citi has a buy rating and a $39.25 price target on ANZ, which has been the analyst favourite among the majors for much of 2026.
Australian banks also remain exceptionally well capitalised by global standards, and their fully franked dividends continue to appeal to income investors in lower tax brackets.
None of those arguments require earnings to accelerate, which is a large part of their appeal to conservative investors.
Foolish takeaway
The 11 August decision matters less for what it does to margins next quarter, and far more for what it signals about the path into 2027.
A hold, followed by a solid CBA result on 12 August, would validate the bulls.
Another hike would sharpen the credit quality debate that the bears have been pressing all year.
Long-term investors in ASX bank shares should watch the arrears line as closely as the cash rate itself, because that is where this cycle will ultimately be decided.
