What Are the Big 4 Companies in New Zealand?

When New Zealanders talk about “the Big 4,” they usually mean one of two very different groups: the four major banks that dominate the country’s finance sector, or the four global accounting and advisory firms that audit its largest companies. Both wield enormous influence over the economy. This guide explains who they are, how they compare, what they are criticised for, and what alternatives exist. It is general information, not financial advice.

The big four banks

New Zealand’s retail banking is dominated by four institutions — ANZ, ASB, BNZ and Westpac — that together hold roughly 85% of the country’s banking assets and around 84% of all bank lending. A defining feature is that all four are subsidiaries of large Australian parent banks.

Quick profiles of each:

• ANZ is the largest, with close to a third of the market. It absorbed the National Bank brand in 2012 (having acquired it in 2003) and is often treated as the benchmark for mortgage and savings rates — see our guide to ANZ mortgage rates.
• ASB — founded in 1847 as the Auckland Savings Bank and now owned by Commonwealth Bank of Australia — is known for digital innovation and consistently high customer-satisfaction scores.
• BNZ (Bank of New Zealand), founded in 1861 and owned by National Australia Bank, is the only big-four bank head-quartered in Wellington and leans heavily into small-business and agribusiness lending; our BNZ guide has more.
• Westpac is a major retail and business bank and holds the contract as the Government’s main banker.

Their scale is striking: combined assets exceed NZ$700 billion, and between them they hold most of the country’s mortgages, savings and business loans. Part of the reason the structure is so stable is Australia’s long-standing “four pillars” policy, which bars the four Australian parents (CBA, Westpac, NAB and ANZ) from merging with one another — effectively locking in the same four-way line-up in New Zealand.

The Reserve Bank of New Zealand regulates them tightly. Each big-four bank must be locally incorporated — operationally separate from its Australian parent — and hold high levels of capital so it can absorb losses without a taxpayer bailout. Since 1 July 2025 there is an added layer of protection for customers: the Depositor Compensation Scheme guarantees eligible deposits up to $100,000 per depositor, per licensed institution, if a bank fails.

The big four are not the only option, and smaller players are often more competitive on price. In 2024 the Commerce Commission published a market study into personal banking services that described the sector as a “stable two-tier oligopoly,” found the majors earn sustained high profits by international standards, and recommended strengthening Kiwibank — the largest New Zealand-owned challenger — and rolling out open banking to sharpen competition. The practical lesson for consumers is to shop around: compare the term deposit rates on offer, run the numbers with a home loan calculator, keep an eye on the current interest rate environment, and remember that a smaller bank such as TSB sometimes posts sharper rates than the majors.

The big four accounting firms

In the professional-services world, “Big 4” means the global networks of Deloitte, PwC, EY and KPMG. They provide audit, tax, consulting and advisory services to most large New Zealand companies and to the government, and between them they audit the vast majority of the NZX 50 — the index of the 50 largest companies on the New Zealand share market.

They operate on a “network” model: each national firm is a separate legal entity that shares a global brand, methodology and quality standards. That scale, reputation and technology are why a Big 4 signature on a set of financial statements carries weight with investors and international markets. In New Zealand the firms are increasingly involved in climate-related disclosures — the mandatory climate reporting that large financial institutions and listed issuers must now produce — where they provide independent assurance of the data. Audit quality itself is monitored by the Financial Markets Authority.

Why only four? The name is a legacy of decades of consolidation. The profession went from a “Big Eight” in the 1980s, through a wave of mergers to a “Big Five,” and then to today’s four after the 2002 collapse of Arthur Andersen in the wake of the Enron scandal. For smaller businesses, mid-tier firms such as BDO and Grant Thornton are growing alternatives.

What is the biggest company in New Zealand?

A closely related question. Among NZX-listed companies, Fisher & Paykel Healthcare is consistently the largest by market capitalisation (the total value of a company’s shares), at roughly NZ$25 billion in 2026, followed by names such as Infratil, Auckland Airport, Meridian Energy and Xero. None of these belong to either “Big 4,” but they anchor New Zealand’s listed corporate landscape. Were the big-four banks’ New Zealand subsidiaries listed independently, they too would rank among the country’s largest companies.

Why they matter — and the criticism

Both sets of Big 4 sit at the centre of the economy. The banks drive lending and investment; the accounting firms underpin corporate transparency; together they employ tens of thousands of people and pay significant tax. But their dominance attracts criticism. In banking, the fact that all four parents are Australian-owned means much of the profit flows across the Tasman, and high market concentration can translate into higher fees and weaker competitive pressure than a more contested market would deliver. Among the accounting firms, critics point to potential conflicts of interest when the same network sells both audit and lucrative consulting work to the same large clients.

The practical takeaway for consumers and businesses is simple: the big four are convenient, well-resourced and safe, but they are not automatically the best deal. Comparing products — and giving the New Zealand-owned alternatives a proper look — is almost always worthwhile.

Important disclaimer

This article is general information about New Zealand’s major banks and accounting firms. It is not financial advice and not a recommendation of any bank, firm or product. Market shares, ownership details and company figures are approximate and change over time — confirm current details directly with the institution before acting. Deposit protection under the Depositor Compensation Scheme is subject to eligibility criteria; check the Reserve Bank of New Zealand for the current rules.

Frequently asked questions

What are the Big 4 companies in New Zealand?

“Big 4” usually refers to one of two groups: the four largest banks (ANZ, ASB, BNZ and Westpac) or the four largest accounting and advisory firms (Deloitte, PwC, EY and KPMG). Both dominate their respective industries by revenue, assets and staff.

Which are the biggest banks in New Zealand?

ANZ, ASB, BNZ and Westpac — all subsidiaries of Australian parent banks — collectively hold roughly 85% of New Zealand’s banking assets and around 84% of lending. ANZ is the largest, with close to a third of the market.

Are New Zealand’s banks Australian-owned?

The big four are: ANZ NZ is owned by ANZ Group, ASB by Commonwealth Bank of Australia, BNZ by National Australia Bank, and Westpac NZ by Westpac Banking Corporation. Kiwibank, by contrast, is 100% New Zealand-owned and is the largest domestic challenger.

Are New Zealand banks safe?

They are considered very stable and are strictly regulated by the Reserve Bank, which requires high capital and liquidity. Since 1 July 2025, eligible deposits are also protected up to $100,000 per depositor, per licensed institution, under the Depositor Compensation Scheme.

Which are the Big 4 accounting firms?

Deloitte, PwC (PricewaterhouseCoopers), EY (Ernst & Young) and KPMG. They dominate global audit, tax and consulting, and in New Zealand they audit most of the NZX 50 and advise major companies and the government.