The past six weeks have seen Commonwealth Bank of Australia (ASX: CBA) shares regain lost ground in the battle with BHP Group Ltd (ASX: BHP) for the biggest ASX stock crown.
Of course, the two S&P/ASX 200 Index (ASX: XJO) titans – the biggest two companies on the ASX by market cap – don't directly compete against each other. And they're not at war!
But there are distinct advantages to holding a dominant position on the ASX, including attracting greater inflows from index-tracking funds.
Here's what's been happening.
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CBA shares closing the gap
Heading into 2026, CBA had held the title of biggest ASX share for almost 18 months.
But Australia's biggest bank relinquished that crown back to BHP on 27 January. Over the next few weeks, the two ASX juggernauts handed that title back and forth as one stock alternately outperformed the other.
But by March, BHP had taken a commanding lead, with the miner's shares buoyed by an iron ore price of around US$110 per tonne and surging copper prices.
That boost came as CBA shares struggled amid persistent analyst warnings over the ASX bank stock's overvaluation relative to its peers. CommBank also faced headwinds from rising investor concerns that ongoing elevated inflation and higher interest rates could lead to lower home loan volumes and higher default rates.
Over the last six weeks, however, BHP's commanding lead has shrunk considerably.
Currently trading for $60.05 apiece, BHP shares have slipped 1.2% since market close on 11 June.
Over this same time, CBA shares have leapt 16.8% to be changing hands for $175.23 at the time of writing on Monday.
This sees CommBank stock commanding a market cap of around $292.9 billion, or just $12.2 billion shy of BHP's current $305.1 billion valuation.
Why is the race back on?
CBA shares are closing the gap on BHP's biggest ASX stock title following a strong year of outperformance from the Aussie mining giant.
Indeed, BHP shares have gained 49.1% over the past 12 months, while CBA stock is up a meagre 0.2%.
That divergent performance has prompted more retail and institutional investors to reevaluate their allocations to the mega-cap ASX shares, with some analysts believing BHP's share price has outpaced its fundamentals.
BHP has also come under pressure with the iron ore price falling back below US$100 per tonne. The industrial metal is currently fetching US$98 per tonne.
And BHP's share came under selling pressure on the heels of the company's June quarter results (Q4 FY 2026).
Fourth-quarter copper production of 491,900 tonnes was down 5% from Q4 FY 2025. And iron ore production of 68.1 million tonnes was down 3% year on year.
