Last checked at 
* Tullow relegated to FTSE 250
* Weir Group remains in the FTSE 100
* AA, Imagination Tech, Virgin Money join FTSE 250
* Afren, Game Digital, Oxford Instruments out of FTSE 250 (Adds detail on reshuffle, background)
By Sudip Kar-Gupta
LONDON, March 4 (Reuters) - Hikma Pharmaceuticals has pushed Tullow Oil out of Britain's benchmark FTSE100 equity index, FTSE Group announced on Wednesday,following a drop in Tullow's stock price and a rise in Hikma'sshares.
Getting into the FTSE 100 can often fuel further demand fora company's shares, since funds that track the FTSE or invest inthe index can then add that stock to their portfolio.
The rankings are decided on market capitalisation. Companieswith the lowest market cap in the FTSE 100 drop into the FTSE250 mid-cap index, and companies with the highest marketcap on the FTSE 250 get promoted into the top index.
Tullow has been hit by a slump in the oil price and concernsthat a boundary dispute between Ivory Coast and Ghana coulddelay a project off the West African coast.
By contrast, in November Hikma raised its annual revenuegrowth target due to strong demand for itsproducts.
Engineering company Weir Group, which had been seenas at risk of being demoted from the FTSE 100, also managed tostay in the top UK equity index.
VIRGIN MONEY TO JOIN FTSE 250
Shares in Tullow Oil closed down 1.3 percent on Wednesday,while Hikma's shares rose 2.5 percent. Tullow Oil shares havefallen around 13 percent since the start of 2015, while Hikmahas risen around 24 percent.
Among other changes, motoring group and car insurer AA Plc -- which floated on the stock market last year -- wonpromotion to the FTSE 250 index.
Imagination Technologies, which supplies graphicsprocessing to Apple Inc ajd British bank Virgin Money are also set to enter the mid-cap index.
Oil producer Afren, which has defaulted on its 2016bonds, will drop out of the FTSE 250 index along with videogames retailer Game Digital and nanotechnology toolsmanufacturer Oxford Instruments.
The changes to the FTSE 100 and 250 indexes will take effectat the start of trading on March 23. (Editing by Atul Prakash; Editing by Andrew Heavens)
