Yahoo! (YHOO) was down 4.7% in preopen Island trading after naming Terry Semel as its chairman and CEO, effiective May 1.

Semel previously was at

AOL Time Warner's


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Warner Bros.

unit, where he served at co-chairman and co-CEO.

He replaces Tim Koogle, who stepped down as CEO of Yahoo! on March 7. Koogle will remain as vice chairman of the Internet media company until August and will retain a seat on the board.

Yahoo! said Semel bought 1 million of its shares.