4 quick ways to assess the CBA share price

Commonwealth Bank of Australia shares trade at roughly 26 times forward earnings, a premium that has stretched further as the bank's cost-to-income ratio improved to 42% in the latest half. That multiple is about 40% above the big-four average of 18.5 times, according to Bloomberg data.

The gap reflects CBA's dominant mortgage book and its lower funding costs. The bank holds roughly a quarter of Australia's home loans, and its deposit base gives it a cheaper source of funding than peers that rely more on wholesale markets. That structural advantage shows up in the net interest margin, which held at 2.08% in the half, flat from a year earlier while rivals saw compression.

The premium also assumes CBA can keep growing earnings when the housing market is slowing. Sydney home prices fell 0.3% in March, the first monthly decline in 18 months, and auction clearance rates have slipped below 60%. A sustained downturn would hit loan growth and potentially push up bad-debt charges, which CBA reported at just 0.12% of gross loans. That is the lowest among the majors.

The other risk is regulatory. APRA has flagged tighter capital requirements for the big four. CBA's common equity tier-one ratio of 12.3% leaves less headroom than Westpac's 12.8% or NAB's 12.6%. If the regulator forces a higher floor, CBA may need to raise equity or cut dividends. The stock currently yields 3.8%.

CBA's cost advantage is real. The valuation already prices in years of perfect execution. A miss on mortgage growth or a regulatory surprise would close the gap quickly. Investors who want to assess the CBA share price can start with the earnings multiple, the net interest margin trajectory, the housing market data, and the APRA capital timeline – the four metrics that pack the most predictive power right now.