Viva Energy Group Ltd (ASX: VEA), NextDC Ltd (ASX: NXT), and National Australia Bank Ltd (ASX: NAB) shares are grabbing financial headlines today.
In morning trade on Monday, two of the blue-chip stocks are trailing the 0.5% losses posted by the S&P/ASX 200 Index (ASX: XJO), while shares in the third are temporarily halted.
Here's what's catching ASX investor interest.

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NAB shares slide on increased risks
NAB shares are taking a hit today.
Shares in the ASX 200 bank stock are down 3.2% at the time of writing, changing hands for $41.17 apiece.
This underperformance follows an operational update from NAB this morning ahead of its half-year (H1 FY 2026) results release, scheduled for 4 May.
NAB shares are under pressure after the bank noted that increased market volatility, fuelled by the conflict in the Middle East, has seen the bank review its credit provisioning and capital settings as at 31 March.
Management said these now better "reflect the risks inherent in our business".
NAB said that sectors including agriculture, transport, and manufacturing are being particularly impacted.
In light of these issues, NAB revealed a $706 million credit impairment charge for H1 2026. The big four Aussie bank also confirmed an accelerated $1.35 billion amortisation charge on its software assets.
Management reaffirmed NAB's full-year FY 2026 cash operating expense growth guidance to be less than 4.6%.
Which brings us to…
NextDC shares halted
NextDC shares aren't moving this morning after the company requested a trading halt prior to the release of the results of an institutional equity raising.
But shares in the ASX 200 data centre operator and developer could get a boost once trading resumes, with the company releasing a strong operational update today.
Among the highlights, the company reported that in the three months to 31 March, its contracted utilisation increased by 60% to 667 megawatts (MW).
And NextDC's forward order book increased by 83% to 544MW.
Management also reaffirmed the company's full-year FY 2026 revenue and underlying earnings before interest, taxes, depreciation and amortisation (EBITDA) guidance.
And finally…
Viva Energy shares sink on refinery fire woes
Atop NextDC and NAB shares, investors are also tuning into Viva Energy shares on Monday.
Shares in the ASX 200 energy stock are down 5.9% in morning trade, changing hands for $2.38 each.
This comes after Viva Energy shares emerged from Thursday's trading halt following the release of an update on last week's fire at its Geelong Refinery. The Geelong Refinery is one of just two refineries remaining in Australia.
Importantly, the company said there were no injuries as a result of the fire.
Viva Energy also revealed that its diesel production will be able to continue to operate at around 80% of capacity, while jet fuel production will operate at around 60% capacity over the short term.
The ASX 200 energy stock said it had enough fuel stocks to ensure a normal supply for its customers. The company aims to return to 90% production capacity levels for both diesel and jet fuel over the coming weeks.