The FT 30 was first calculated in 1935 by the Financial Times. The index started at a base level of 100, and was calculated from a subjective collection of 30 major companies – which in the early years were concentrated in the industrial and retailing sectors.
For a long time the index was the best known performance measure of the UK stock market. But the index become less representative of the whole market. Also the index was price-weighted (like the DJIA), and not market-capitalisation-weighted. Although the index was calculated every hour, the increasing sophistication of the market needed an index calculated every minute and so the FT 30 has been usurped by the FTSE 100.