Big Four is the colloquial name for the four main banks in several countries, where the banking industry is dominated by just four institutions and where the phrase has gained currency.

In Australia, the "Big Four" refers to the four largest banks by market share, who between them hold 85% of the home loan markets in the country. These are:

The government policy until 2011 was to maintain this status quo, it was called the four pillars policy. During the Global Recession of 2008-09, Westpac acquired St George Bank by and the Commonwealth Bank acquired BankWest.

During the 1920s the term “Big Four” applied to the Four Northern Banks of the Republic of China (i.e. the four most capitalized commercial banks in Northern China). These were the Yien Yieh Commercial Bank, the Kincheng Banking Corporation, the Continental Bank and the China & South Sea Bank. These were contrasted with the Three Southern Banks of Southern China.

By 1949 the Big Four were the Bank of China, the Bank of Communications, the Central Bank of China and the Farmers Bank of China (and with Central Trust of China, Postal Savings and Remittance Bureau of China, Central Cooperative Treasury of China, called as "Big Four Banks, Two Bureaus, One Treasury" or "四行两局一库").

Roger Montgomery (1925–2003) was a city planner, urban designer, architect, and educator.

He was born in New York City to parents Graham Livingston Montgomery and Anne Cook and lived in Greenwich Village until 1930, when he moved to Port Washington, Long Island. Roger's father died suddenly from a heart attack in 1942. In 1945 he was accepted into the army, where he served in an intelligence unit in occupied Germany as a radio operator. On April 23, 1949 Roger married Oberlin College graduate Mary Hoyt. Roger has four sons, Richard Wallace (born 1956), Thomas Vinton (1958), John 1960, and Peter George (1965). In 1957 Roger was diagnosed with multiple sclerosis. He died of cancer on October 25, 2003.

Roger attended a John Dewey-influenced grade school in Port Washington, which emphasized mechanical skills over traditional subjects such as reading and writing. In high school he was voted ‘Most Likely to Succeed’ and ‘The Great Orator’. He was excused from military service in 1941 because of a punctured eardrum and subsequently enrolled in Oberlin College, but was dismissed from the college in 1945. Roger began his architectural work in 1948 as an apprentice in Springfield, Ohio and was soon successful, in part because of a shortage of architects and large post-war boom in construction. From 1955 to 1956 Roger attended the Harvard Graduate School of Design where he received a Masters of Architecture degree under professors Josep Lluís Sert and Sigfried Giedion, while studying with classmates Fumihiko Maki and Ben Weese.