Total assets of Australian banks are estimated to be approximately A$4.0 trillion. ANZ, Commonwealth, Westpac and National Australia Bank are the four largest domestic banks providing a complete range of retail and corporate banking services. The big four banks have an Aa3 rating from Moody’s and AA- from Standard & Poor's. Only nine of the world’s top 100 banks enjoy a rating of AA or higher. Australia's government has a "four pillars" policy that prevents mergers between the big four banking institutions. The banking regulation in the country is extensive and detailed. It is split between APRA (Australian Prudential Regulation Authority) and ASIC (Australian Securities and Investment Commission). APRA, established in 1998, controls the credit unions, banks, building and friendly societies, insurance companies as well as members of the superannuation sector. The superannuation industry is a significant part of financial system, with total assets of approximately $2 trillion or 50% the Australian banking system. Foreign banks are also well represented in the Australian market. The majority of them are focused on commercial banking and capital market activities.
Five Largest Banks
| Rank | Bank | Total assets, A$b | Loans, A$b | Deposits, A$b | Balance Sheet |
| 1 | Commonwealth Bank of Australia | 1,149.81 | 843.950 | 815.124 | 31.12.2021 |
| 2 | ANZ Banking Group | 978.857 | 629.719 | 631.290 | 30.09.2021 |
| 3 | Westpac | 935.877 | 709.784 | 626.955 | 30.09.2021 |
| 4 | National Australia Bank | 925.968 | 728.702 | 547.775 | 30.09.2021 |
| 5 | Macquarie Group | 348.567 | 118.359 | 91.736 | 30.09.2021 |
Customer Satisfaction Rating:
Credit Unions: 88.1%
Building Societies: 90.6%
Banks: 74.3%
Major Banks: 78.9%
(Source: Roy Morgan Research)
Five Largest Credit Unions in Australia
| Rank | Name | State | Assets (A$m, FY 2018) | Deposits (A$m, FY 2018) |
| 1 | Credit Union Australia | QLD | 14,323 | 9,220 |
| 2 | People's Choice Credit Union | SA | 8,391 | 6,114 |
| 3 | Queensland Country Credit Union | QLD | 2,167 | 1,881 |
| 4 | Bananacoast Community Credit Union | NSW | 1,700 | 1,543 |
| 5 | Credit Union SA | SA | 1,065 | 945,5 |