Carl Icahn lowers Yahoo stake in Q4, adds Genzyme

* Investor's Yahoo shares at 12 mln from 62.9 mln-filings

* Genzyme holdings up amid focus on biotech company

By Ross Kerber and Alexei Oreskovic

BOSTON/SAN FRANCISCO, Feb 12 (Reuters) - Billionaire investor Carl Icahn cut his stake in search firm Yahoo Inc (YHOO.O) but added shares in biotechnology company Genzyme Corp GENZ.O, securities filings showed on Friday.

Filings by Icahn and his firm Icahn Capital LP showed the well-known investor winding down his holdings in Yahoo after settling a squabble with the company's management in recent years.

Icahn's stake in Yahoo stood at 12 million shares as of February 12, down from 62.9 million shares at the end of August, according to the filings.

Icahn amassed his stake in Yahoo -- which at one point represented 5.4 percent of outstanding shares -- amid the company's contentious acquisition talks with Microsoft Corp. (MSFT.O) in 2008.

After Yahoo rejected Microsoft's $47.5 billion offer, Icahn mounted a proxy contest seeking to oust the Yahoo directors. He eventually reached a settlement that gave Icahn and two of his director nominees seats on the company's board.

Icahn resigned from Yahoo's board in October 2009, after Yahoo signed a 10-year deal with Microsoft in which Yahoo will use Microsoft's back-end search technology on its Web portal.

But Friday's filing showed Icahn may be girding to press for changes at another company, Massachusetts biotechnology company Genzyme. His holdings rose to 4.8 million shares as of Dec. 31 from 1.5 million shares three months earlier.

A source has told Reuters Icahn may consider a proxy battle with Genzyme's management, which in turn has struck an alliance with rival investor Ralph Whitworth.

Icahn also has forced board changes at another Cambridge biotech firm, Biogen Idec Inc (BIIB.O). His stake in that company stayed the same around 16 million shares through December, the filings showed.

Another change in the quarter was a stake of 12.1 million shares Icahn took in financial firm CIT Group Inc (CIT.N), according to the filings. (Reporting by Ross Kerber and Alexei Oreskovic; Editing by David Gregorio)