When you're thinking about where to keep your hard-earned money in Australia, it's hard to ignore the sheer presence of the 'Big Four' banks: Commonwealth Bank (CBA), Westpac, National Australia Bank (NAB), and Australia and New Zealand Banking Group (ANZ). These giants collectively hold about 70% of the Australian financial market, managing assets that dwarf those of their smaller competitors. As of early 2025, their combined assets exceeded a staggering $3.80 trillion, a significant chunk of the nation's nearly $5.5 trillion banking sector.
It's fascinating to see how these institutions have grown. They're not just big; they're also bound by the 'Four Pillars Policy,' a law that essentially prevents them from merging with each other. This policy, alongside their massive scale, sets them apart. Over the years, they've strategically expanded by acquiring smaller banks and financial players, solidifying their dominance. And while they operate with a certain autonomy, it's important to remember they're all under the watchful eyes of regulators like APRA, ASIC, the RBA, and the Department of Treasury.
Let's break down these four powerhouses a bit more. CBA, though the youngest, established in 1911 and privatised in 1996, stands tall as Australia's largest bank, both in terms of total assets and market capitalisation. It even served as the nation's central bank for a good while before the RBA took over that role.
Westpac currently holds the second spot in market capitalisation, a position it's fiercely contested. Its growth has been significantly boosted by strategic mergers, like the one with St.George Bank in 2008, along with acquisitions of BankSA and RAMS. NAB, on the other hand, has a history stretching back to the 19th century, formed from the merger of two established banks. Its asset base includes subsidiaries like UBank and Bank of New Zealand, and it's been active in acquiring newer players like neobank :86 400 and Citi's retail banking portfolio.
ANZ, while currently the smallest of the Big Four, is poised for significant growth with its acquisition of Suncorp Bank. Once this deal is finalised, ANZ's assets will surge past $800 billion, making it a much larger entity. Suncorp's banking arm alone was a substantial player, ranking among the top 10 in Australia.
When it comes to where Australians entrust their savings, the Big Four are clearly the preferred choice. Their combined household deposits represent over 70% of all cash deposits in the country. This includes everything from everyday transaction accounts to term deposits and savings accounts. While they all offer a variety of savings products, and their interest rates and features are often quite similar, the 'best' one really comes down to your personal savings goals and what aligns best with your financial strategy. It’s always worth comparing those bonus interest rates and base variable rates to make sure you’re getting the most out of your money.
