National Australia Bank Ltd (ASX: NAB) shares are on the slide on Monday morning.
At the time of writing, the big four bank's shares are down 4% to $40.73.
This compares to the S&P/ASX 200 Index (ASX: XJO), which is down 0.4% in early trade.

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Why are NAB shares sinking?
This morning, NAB revealed that it has reviewed its credit provisioning and capital settings to better reflect the risks in the market caused by the conflict in the Middle East.
According to the release, this has seen NAB increase its forward-looking collective provisions and announce plans to apply a discount and partial underwrite its dividend reinvestment plan (DRP).
NAB has also made changes to its software capitalisation policy to more closely align to an environment of rapid technological change.
Credit impairment charges
NAB expects first-half credit impairment charges to be $706 million.
This includes $300 million related to the following movements in forward looking collective provisions:
- $152 million increase in the Economic Adjustment reflecting updates to the Base economic forecast and a 2.5% increase in the weighting to the Australian Downside economic scenario to 45%.
- $201 million increase in Forward Looking Adjustments (FLAs) for potential stress which may emerge in sectors more likely to be impacted by fuel supply and cost issues related to the Middle East conflict.
- $53 million release in FLAs where the expected risk has either not eventuated or is now reflected in underlying provisioning.
The ratio of collective provisions to credit risk weighted assets is expected to be 1.35% at March 2026. This is up from 1.31% at December 2025.
Underlying provision charges are expected to be $406 million, which is reflective of Individual Assessed provision charges of $541 million, partially offset by portfolio movements, which NAB advised have driven a $135 million write-back of the underlying collective provision.
DRP update
Interest rate volatility and the weakening of the New Zealand Dollar in the second quarter, together with the $300 million net increase in forward looking collective provisions, has reduced NAB's Common Equity Tier 1 (CET1) ratio by approximately 20 basis points.
Furthermore, NAB's credit risk-weighted assets at 31 March 2026 were impacted by a $4.2 billion overlay which applied to NAB's internally rated credit models to reflect updates to certain probability of default models.
In light of this and ongoing uncertainty, NAB revealed that it is taking action to strengthen its capital position and balance sheet resilience. This will see the bank apply a 1.5% discount to the half-year DRP and partially underwrite it.
The combination of these actions is expected to raise up to $1.8 billion and contribute up to approximately 40 basis points to its CET1 ratio in the second half.