Banking market concentration in Australia and New Zealand exceeds most comparable developed economies, with major implications for business lending costs, consumer fees, and financial system stability.

Australia’s banking sector is dominated by the “Big Four”—Commonwealth Bank, Westpac, NAB, and ANZ—which collectively hold approximately 75% of residential mortgages and similar shares of business lending and deposits. This concentration has increased over the past two decades through merger and acquisition activity and the exit or acquisition of smaller competitors.

New Zealand’s concentration is even more extreme. ANZ, ASB (owned by Commonwealth Bank), BNZ (owned by NAB), and Westpac NZ control roughly 85% of the banking market. The major players are either Australian-owned or Australian subsidiaries, creating additional policy complications around financial stability and regulatory authority.

Interest rate margins in both countries are wider than many international peers. The gap between deposit rates paid to savers and lending rates charged to borrowers provides substantial profit margins for banks. Australian major banks have consistently delivered return on equity around 10-12%, well above their cost of capital, suggesting market power allows above-competitive returns.

Mortgage pricing shows interesting patterns. Headline interest rates on new mortgages are often competitive, particularly for borrowers who actively negotiate or switch banks. But existing customer rates tend to drift higher as banks apply rate increases faster than rate decreases. The “loyalty tax” where existing customers pay more than new customers is well-documented but persists.

Business lending costs are generally higher than residential mortgages despite commercial lending often being secured. The risk-based pricing explanation doesn’t fully account for the spread. SME lending is particularly expensive, partly reflecting higher servicing costs for smaller loans but also market power allowing banks to extract higher margins.

Transaction fees and account-keeping fees have declined as regulatory pressure and fintech competition forced fee reductions. But banks have protected overall revenue through higher lending margins. The shift from visible fees to less visible interest margin extraction is arguably worse for transparency and competitive pressure.

New entrants have struggled to achieve scale. Multiple digital banks and challengers have launched in both markets over the past decade. Some have carved out niches, but none has achieved market share above 2-3%. The barriers to entry include customer acquisition costs, regulatory capital requirements, and the network effects and brand strength of incumbents.

Customer switching rates remain low despite initiatives to make changing banks easier. In Australia, roughly 4-5% of customers switch primary banking relationships annually. New Zealand’s switching rate is similar. The combination of inertia, perceived hassle, and concern about credit history impacts creates sticky customer relationships that incumbents exploit.

The regulatory response has been incremental rather than transformative. Open banking regulations are being implemented to enable data portability and theoretically make switching easier. Whether this drives meaningful competition remains to be seen—early evidence suggests limited consumer uptake of open banking capabilities.

Profitability through market cycles shows the value of oligopoly positions. Australian major banks maintained profitability through the 2008-2009 global financial crisis when many international banks faced existential crises. More recently, they’ve navigated COVID-19 with limited damage. This stability benefits financial system safety but also demonstrates how market concentration insulates banks from competitive pressure.

The vertical integration between banking and wealth management creates additional competition concerns. Banks that provide both banking and financial advice face inherent conflicts of interest. The Banking Royal Commission in Australia exposed numerous instances where advice was skewed toward bank products regardless of whether they served customer interests. Remediation and regulatory changes followed, but structural conflicts remain.

Small business lending has been a particular concern. The banks’ risk appetite for SME lending declined following the Global Financial Crisis and has never fully recovered. Alternative lenders have partially filled the gap but typically at much higher interest rates. Many viable businesses struggle to access affordable capital due to conservative bank lending criteria.

Agricultural lending represents a specialized segment where fewer banks compete, creating even greater concentration. This matters given agriculture’s importance to both economies. The relationship between banks and farming communities is complex—long-standing relationships provide continuity but also create dependencies and power imbalances.

The too-big-to-fail problem is particularly acute in concentrated banking markets. If one of Australia’s major banks failed, the economic and financial impact would be catastrophic. Government would almost certainly intervene to prevent collapse. Banks implicitly benefit from government guarantee, reducing their borrowing costs and creating moral hazard.

New Zealand’s position as a small economy dependent on four large Australian-owned banks creates unique vulnerabilities. In a crisis, would Australian parent banks prioritize their New Zealand subsidiaries or their Australian operations? The regulatory framework attempts to address this through ring-fencing requirements, but concerns persist.

Fintech disruption was supposed to transform banking competition. While fintech has created alternatives in specific segments—payments, foreign exchange, buy-now-pay-later—it hasn’t fundamentally disrupted core banking functions of deposit-taking and lending. The major banks have adapted by either acquiring fintechs, partnering with them, or replicating their offerings.

Cryptocurrency and decentralized finance represent potential longer-term threats to traditional banking, but adoption remains limited. The banks have taken “wait and see” approaches—acknowledging the technology might matter eventually while maintaining that current crypto usage doesn’t threaten core banking business.

The business case for increased competition is debatable. Would more competitive banking markets deliver lower costs to consumers and businesses? Almost certainly. But would they deliver less stable financial systems? Possibly. The trade-off between competition and stability is real, though often overstated by incumbent banks defending their positions.

International comparisons provide context. Australia and New Zealand’s banking concentration exceeds Canada (five major banks), the UK (four dominant banks plus more meaningful challengers), and the US (much more fragmented). Those more competitive markets generally deliver narrower interest margins and lower fees.

The public policy response could include structural separation—breaking up major banks. But political will for such dramatic action doesn’t exist, and the complexity and transition risks are substantial. More incremental approaches focus on reducing barriers to entry and making switching easier.

Looking forward, the concentration is likely to persist. Absent regulatory intervention forcing structural change, the incumbents’ advantages are too substantial for new entrants to overcome. The best-case scenario is probably that fintech provides meaningful competition in specific product categories, forcing major banks to improve offerings and pricing in those areas while maintaining overall market dominance.

For business and consumer customers, the practical implication is that negotiating power and willingness to switch remain the primary tools for achieving better pricing. Those who actively manage banking relationships and leverage competition among the major banks achieve materially better outcomes than passive customers who accept whatever their bank offers.

The concentration in Australia and New Zealand banking markets represents a clear case where market structure creates outcomes that benefit banks more than customers. Whether this is sustainable long-term or whether technology eventually disrupts the oligopoly remains an open question.