The FT 30 lost about 75% of its value during the 1973–1974 stock-market crash.
The Financial Times Ordinary Share Index, commonly called the FT 30, was a major British share index before the FTSE 100 became the principal market benchmark. It reached a high in May 1972 and then suffered a prolonged collapse. By December 1974, the index was approximately 73% below its peak, one of the sharpest declines experienced by a major developed-market index.
The crash was part of an international bear market. Important pressures included inflation, the 1973 oil shock, slowing economic growth, political uncertainty, and the end of the long postwar expansion. Britain also faced industrial disputes and serious economic difficulties during the period.
The FT 30 is often confused with the later FTSE 100, which began in 1984. The FT 30 continued to exist, but it was gradually overshadowed by the newer, broader index. The 1973–1974 crash affected markets worldwide rather than being solely a British event.