1817; 200 years ago (1817) (as Bank of New South Wales)

Westpac Banking Corporation, more commonly known as Westpac, is an Australian bank and financial-services provider headquartered in Westpac Place, Sydney. It is one of Australia's "big four" banks. Its name is a portmanteau of "Western-Pacific".

As of November 2015, Westpac has 13.1 million customers, and is Australia's largest branch network, with 1429 branches and a network of 3850 ATMs. The bank is Australia's second-largest bank by assets. It is also the second-largest bank in New Zealand.

On 29 January 2015, Bank South Pacific announced that it had entered into an agreement to acquire Westpac's banking operations in Samoa, Cook Islands, Solomon Islands, Vanuatu and Tonga for A$125 million.

Established in Sydney in 1817, the Bank of New South Wales (BNSW) was the first bank in Australia. Edward Smith Hall was its first cashier and secretary. During the 19th and early 20th century, the Bank opened branches first throughout Australia and Oceania, at Moreton Bay (Brisbane) in 1850, then in Victoria (1851), New Zealand (1861), South Australia (1877), Western Australia (1883), Fiji (1901), Papua New Guinea (1910) and Tasmania (1910).

The structure involves five key divisions including: Consumer Bank, Commercial and Business Bank, BT Financial Group, Westpac Institutional Bank and Westpac New Zealand. These five divisions serve more than 13 million customers.

Consumer Bank is responsible for sales and service of its 9 million consumer customers in Australia, assisting them with their everyday banking needs. The division covers all consumer banking products and services under the Westpac, St.George, BankSA, Bank of Melbourne and RAMS brands.

Activities are conducted through the Consumer Bank’s nationwide network of 1,429 branches, third-party distributors, call centres, 3,850 ATMs, EFTPOS terminals and internet banking services.

The Business Bank is responsible for sales and service of its small-to-medium enterprise, commercial and agribusiness customers in Australia, as well as asset and equipment finance and operates under the Westpac, St.George, BankSA and Bank of Melbourne brands.

Business and corporate customers (businesses with facilities typically up to $150 million) are provided with a wide range of banking and financial products and services, including specialist advice for cash flow finance, trade finance, automotive and equipment finance, property finance, transaction banking and treasury services. Sales and service activities for business and corporate customers are conducted by relationship managers via business banking centres, internet and customer service centre channels.

BT Financial Group (BTFG) is the wealth management arm of the Westpac Group, which, following the merger with St.George Bank Limited, also includes the wealth division of St.George.

BTFG designs, creates and distributes financial products that are designed to help its customers achieve their financial goals by administering, managing and protecting their assets.

Funds Management operations include the manufacture and distribution of investment, superannuation and retirement products, investment platforms including BT Wrap and Asgard, private banking, financial planning as well as equity capability and broking. Insurance solutions cover the manufacturing and distribution of life, general and lenders mortgage insurance.

Westpac Institutional Bank (WIB) delivers a broad range of financial services to commercial, corporate, institutional and government customers.

WIB operates through dedicated industry relationship and specialist product teams, with expert knowledge in transactional banking, financial and debt capital markets, specialised capital, margin lending, broking and alternative investment solutions.

Customers are supported through operations in Australia, New Zealand, the US, the UK, and Asian centres.

In 1861 the Bank of New South Wales opened seven branches in New Zealand. Some of the old buildings still stand, including one in Oamaru and another in Tokomaru Bay. Today this unit offers a whole range of consumer and corporate services to clients throughout New Zealand. It is the dominant provider of banking services to small to medium business, corporate and institutional organisations, and is the banker of the New Zealand government. Currently Westpac is the second largest bank in New Zealand, after the merger of ANZ and National Bank of New Zealand, with around 1.5 million customers, 3,000 shareholders and 197 branches nationwide.

On 29 September 2006 the New Zealand Commerce Commission forced Westpac to pay NZ$5.1 million for hidden foreign transaction fees; most of the fine is reimbursement to affected customers, in the order of 12% of the fees actually charged. All other banks operating in New Zealand have either already been fined or are awaiting a court case.

In October 2009 Westpac Banking Corporation (New Zealand branch) was ordered to pay the Inland Revenue Department (New Zealand) NZ$961 million in avoided taxes.

On 22 July 2014, Westpac publicly announced that they would pilot their host card emulation (HCE) mobile payments technology to customers. Westpac became the first bank in New Zealand to actively bring HCE mobile payments to market and one of only a handful of banks globally to be using the innovative ‘digital wallet’ technology.

Westpac's three-month trial, which uses Carta Worldwide HCE technology, enables customers to securely store and access credit and debit card information in a remote and hosted ‘cloud’ environment, enabling customers to use their Android smartphones as digital wallets.

Soon after, in August 2014, Westpac NZ announced that it would be releasing the world's first augmented bank app, which adds layers of functionality to the digital wallet by enabling users to check account balances, view previous spending behaviours, pay bills and locate their nearest Westpac NZ branch or ATM. The app is also viewable in a 3D format by supported devices.

Westpac is a member of the Global ATM Alliance, a joint venture of several major international banks that allows customers of the banks to use their ATM card or check card at another bank within the Global ATM Alliance with no fees when traveling internationally. Other participating banks are Allied Irish Banks (Ireland), Barclays (in the UK, Spain and parts of Africa), Bank of America (US), BNP Paribas (France), Ukrsibbank (Ukraine), Deutsche Bank (in Germany, Spain, Italy, Poland), and Scotiabank (in Canada, Chile, Mexico among many other countries).

This unit of both the Australian and New Zealand Bank offers banking facilities to those migrating to either New Zealand or Australia. Bank accounts for migrants can be opened before people arrive in the country using their easy account opening process. Credit cards and mortgages can even be approved before arrival. Westpac Migrant Banking has a representative office in London where accounts can be arranged, although the process can be done remotely from any country. Westpac plans to open a retail branch in London in 2011.

Westpac operates in seven south Pacific nations; the unit is headquartered in Sydney. The financial services offered include electronic banking (via online banking, ATMs and EFTPOS), deposit, loan, transaction accounts and international trade facilities to personal and business customers. Westpac Fiji is Westpac's Fijian operation. It is one of the largest banks in the country and has a 40% market share.

Westpac Pacific Banking is a member of the Global Banking Alliance for Women, supporting initiatives in the Pacific to help women prosper and grow.

In 2016 Westpac was mentioned in a lawsuit by Australian Securities and Investments Commission for manipulation of Australian benchmark interest rates.

In 2009, a Westpac-owned entity secured US$1.09 billion from the US Federal Reserve. Commentary suggests this was an unusual move for the bank, given its relatively minor position in North America. The borrowings by Westpac occurred at the height of the global financial crisis and was part of a Federal Reserve move to stabilise financial markets globally. The public and government attention of the borrowings followed the release of the information by the Federal Reserve in 2011, not Westpac.

Westpac has recently come under criticism from climate-change organisations in New Zealand for its role in funding mining company Bathurst, which has gained resource consent to mine coal on the Denniston Plateau on the West Coast of the South Island. Opponents have claimed that the mine will release up to 218 million tonnes of carbon dioxide, which will worsen the effects of anthropogenic climate change, as well as significantly damage an important ecosystem. Westpac have largely ignored these claims, despite over one hundred customers leaving the company because of this issue.

In 2002 Westpac released a social impact report that outlined the bank's plan to meet international standards in the area of corporate social responsibility. This led to Westpac's assessment as the global sustainability leader for the banking sector in the Dow Jones Sustainability Index from 2004 to 2007.

Westpac has been criticised for backing logging operations on the Solomon Islands that destroy virgin rainforests. Because of this engagement, the Australian Greens have called for the Banksia Awards to be withdrawn from Westpac.