The ASX 200 is dominated by two blue-chip companies:
These companies are the largest ASX-listed stocks by market cap. For this reason, they make up a fundamental part of many investors' portfolios.
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You might own these shares without even knowing it
Many Australians own shares in BHP and Commonwealth Bank without ever buying them directly.
This is because their superannuation funds and many ASX-listed ETFs automatically invest in the largest companies on the Australian share market.
Since BHP and Commonwealth Bank are among the largest companies in the ASX, they're common holdings in diversified super funds and broad-market ETFs, meaning millions of Australians have exposure to these shares simply through their retirement savings or index investments.
According to a recent report, these two companies account for almost 20% of the ASX 200 index.
So if you own an ASX 200 or 300 tracking ETF, the performance of CBA and BHP shares have a big impact on the performance of your portfolio.
A wide gap in 2026
Despite the two companies being vital parts of portfolios, they have performed very differently so far this year.
BHP shares have risen by 24% year to date, while CBA shares are up just 4%.
BHP's 2026 rally has been driven by genuine structural tailwinds.
Copper prices have surged on electrification, AI-driven data centre demand, and grid upgrades. For the first time in the company's history, copper now contributes more than half of group earnings.
A resilient iron ore price has added further support, giving BHP two strong earnings engines rather than one and thanks to the operating leverage inherent in mining, that extra revenue flows largely to the bottom line and the dividend.
Meanwhile, CBA's flat performance reflects a different dynamic: the bank continues to deliver solid results, with growing cash earnings and healthy lending volumes, but it already trades at a significant valuation premium to its big four peers.
So are these shares a buy? Here is the glass half full and glass half empty case for both.
The bull and bear case
For those looking for a reason to buy BHP shares, the bull case is simple: Copper and iron ore prices are strong, and copper demand looks set to keep growing thanks to AI, data centres, and electrification.
However on the flip side, BHP shares have already risen 50% in the last 12 months.
This means much of the good news may be priced in. Furthermore, a pullback in copper or iron ore prices, or rising costs on projects could quickly compress margins.
Meanwhile, for CBA shares optimists would argue CBA's premium valuation is earned through best-in-class execution, a dominant deposit franchise, superior technology investment, and consistent market share gains in a stable banking sector.
However, bears see a stock priced for perfection, trading well above peers.
This suggests limited room for further upside – and outsized downside risk if growth disappoints or Australian housing conditions deteriorate.
