Companies wanting to be included in the FTSE UK Index Series will have to have to raise their minimum free float requirement from 15% to 25%, FTSE Group has said.After consulting with "market participants from all sectors of the investment community", the index and analytical solutions provider has decided to up the percentage target of shares held by the public in London-listed companies from 1 January next year for all new businesses wishing to join."Both FTSE and our shareholder, the London Stock Exchange Group recognise that this strong stance on governance underpins the value of our business," said FTSE's Chief Executive Officer Mark Makepeace.However, these new guidelines do not affect companies that are incorporated outside the UK; these are already subject to a free float requirement of 50%.According to FTSE, just five stocks listed on the FTSE All-Share index currently do not meet the 25% free float requirement: Eurasian Natural Resources Corp (ENRC); Essar Energy; Evraz; Ferrexpo; and Fresnillo.These companies will not have to meet the January deadline (as they are already listed) but will have just 24 months to increase their free float to 25%.FTSE notes that Glencore, a non-UK incorporated firm, does not meet the 50% nationality rule but intends to meet this target in May 2012.BC