UPDATE 1-Bristol-Myers Squibb CEO buys 100,000 shares

(Adds background on Bristol-Myers earnings, additional byline)

By Kristina Cooke and Ransdell Pierson

NEW YORK, May 8 (Reuters) - The chief executive of drugmaker Bristol-Myers Squibb Co (BMY.N: Quote, Profile, Research, Stock Buzz) bought 100,000 company shares in his first open-market purchase since taking the top post nearly two years ago, according to a regulatory filing on Thursday.

James Cornelius purchased $2.3 million worth of stock on Wednesday for $22.70 to $22.92 a share, according to a U.S. Securities and Exchange Commission filing.

On the same day, the drugmaker said it was evaluating its 2008 earnings forecast and would update its full-year outlook by the end of the second quarter. For details, see [ID:nWNAS2439]

Cornelius, who became chief executive in 2006, is the first insider to directly buy on the open market since at least February 2001, according to insider filing tracker InsiderScore.com.

Bristol-Myers Squibb shares, which were little changed at $22.81 on Thursday, are down 14.3 percent year-to-date.

The chief executive of rival Schering-Plough Corp (SGP.N: Quote, Profile, Research, Stock Buzz), Fred Hassan, bought about $2 million of his company's common stock, or 110,000 shares, two weeks ago, keeping an earlier pledge to make the personal investment as a vote of confidence in the struggling drugmaker.

Hassan announced his plans to buy the stock on Jan. 18, after a failed clinical trial of the company's big-selling Vytorin cholesterol drug spurred a 20 percent decline in the shares that week.