UPDATE 1-Top Bristol-Myers shareholder does not support $74 bln Celgene deal

Bristol-Myers Squibb Co's top shareholder Wellington Management said on Wednesday that it did not support the U.S. drugmaker's $74 billion purchase of biotech Celgene Corp, saying the deal is too risky.

Wellington Management owns about 8 percent of Bristol-Myers shares and was the largest institutional holder as of Feb. 25. Celgene shares fell 8.5 percent after the Wellington statement was released, while Bristol-Myers shares rose 3 percent.

Bristol-Myers said in January that it would buy New Jersey-based Celgene, combining two of the world's largest cancer drug businesses in the biggest pharmaceutical deal ever. Wellington said it had concluded that the deal asks Bristol-Myers shareholders to accept too much risk and that the terms offer the company's shares to Celgene shareholders at a price well below the implied asset value.

The investment manager also said successful execution of the deal could be more difficult to achieve than depicted by company management. Neither Bristol-Myers nor Celgene could immediately be reached for comment.

The Wellington statement comes a week after Bristol-Myers said that activist hedge fund Starboard Value LP intends to nominate five directors to the Bristol-Myers board. Reuters reported in February that Starboard was working with a proxy solicitor to gauge the level of support among Bristol-Myers shareholders for the Celgene deal. If it finds enough discontent, Starboard could agitate against it. (Reporting by Ankur Banerjee in Bengaluru; Editing by Sriraj Kalluvila and Bill Berkrot)