The FTSE 100 was determined by stock market capitalization at close on Tuesday 11th December, and the changes will come into effect on Christmas Eve.
G4S has been a consistent performer over the past year, starting in January at 186p and rising gradually to its current level of over 220p. Its current market capitalization is around GB pound 2.8 bn and its shares closed on Wednesday at 224.25p.
By comparison, ArmourGroup has a market capitalisation of GB pound 18.95m and Mitie of GB pound 872.72m.
Group 4 Securicor was formed in July 2004 when Securicor and Group 4 merged. It now operates in over 100 countries in the world with over 340,000 employees.
Changes to the index, which happen quarterly, are designed to ensure that it remains an accurate representation of the UK’s investable market capitalisation. This is important, as many pension funds and investment portfolios track companies in the FTSE indices.
Troubled bank Northern Rock was the most high-profile casualty of the re-shuffle. Its shares had been trading at GB pound 12 at the start of the year, but are now trading for below 100p.
The size of the shake-up reflects the effect that the credit crunch has had on London’s markets. The last time movements of this magnitude were seen was in September 2001 when eight tech firms were knocked out following the bursting of the tech bubble.
The other new companies in the index are Cairn Energy, Kelda Group, TUI Travel, FirstGroup, Admiral Group and Thomas Cook Group.
Falling out of the index and into the FTSE 250 are Tate & Lyle, Daily Mail, Mitchells & Butlers, Punch Taverns, DSG International and Barratt Developments.