UPDATE 1-Berkeley promoted to FTSE 100 index, replaces Weir Group

* Berkeley joins FTSE 100, Weir Group out in quarterlyreshuffle

* Sophos, Circassia, P2P Global added in FTSE 250 index

* Lonmin, James Fisher, Premier Farnell leave mid-cap index

By Atul Prakash

LONDON, Sept 2 (Reuters) - London-focused housebuilderBerkeley Group has pushed valve and pump maker WeirGroup out of Britain's blue-chip FTSE 100 index, global index provider FTSE Russell said on Wednesday,following sharp moves in their share prices.

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. Firmswith the lowest market cap in the FTSE 100 drop into the FTSE250 mid-cap index every quarter, and companies with thehighest market cap on the FTSE 250 get promoted into the topindex.

Shares in Berkeley Group, which operates at the high end ofthe property market, have surged 35 percent due to its strongperformance. It posted a pretax profit of 539.7 million pounds($826.23 million) in the year through April, much above the470.1 million forecast in a Reuters poll.

The group has said that the number of homes it builds isexpected to increase by roughly 20 percent in the year throughApril 2017.

In contrast, Weir Group shares have fallen about 27 percentin 2015. It posted a 40 percent fall in first-half pretax profitas it struggled with a slump in U.S. oil and gas drillingactivity.

Berkeley shares closed 2.3 percent higher on Wednesday,while Weir Group ended nearly 1 percent lower.

Among other changes, Sophos Group, a provider ofcloud-enabled end-user and network security solutions, hasjoined the FTSE 250 mid-cap index.

Circassia Pharmaceuticals, a UK-based specialitybiopharmaceutical company focused on the development ofimmunotherapies, and P2P Global, which invests incredit assets originated by online lenders, have also enteredBritain's mid-cap share index.

The companies leaving the FTSE 250 index are: SouthAfrica-focused platinum producer Lonmin, marineengineering services provider James Fisher & Sons andEngineering supply group Premier Farnell.

The changes to the FTSE 100 and 250 indexes will take effectat the start of trading on Sept. 21.

($1 = 0.6532 pounds) (Reporting by Atul Prakash; Editing by Mark Heinrich)