The British FT 30 index fell about 73% during the 1973–1974 stock-market crash.
The FT 30, formally the Financial Times Ordinary Share Index, was a leading measure of large British companies before the FTSE 100 became the country’s best-known benchmark. During the crash, it declined from a high of 540.60 in May 1972 to a low of 146.81 in December 1974, a fall of roughly 73%.
The downturn was part of a broader international bear market. Inflation was accelerating, economic growth weakened, and the 1973 oil crisis sharply increased energy costs after the Yom Kippur War. In Britain, industrial disruption and the three-day week added to economic strain.
The FT 30 is often confused with the FTSE 100, which was launched in 1984. The older index had only 30 companies and used a geometric calculation, unlike the later capitalization-weighted FTSE 100. The crash’s exact percentage can vary slightly depending on whether closing or intraday figures are used.