“It’s clear there’s a conflict of interest,” said Charles M. Elson, director of the John L. Weinberg Center for Corporate Governance at the University of Delaware. “Unless earnings per share are adjusted to reflect the buyback, then to base a bonus on raw earnings per share is problematic. It doesn’t purely reflect performance.”

In addition, executives, who are often large shareholders, stand to benefit from even a small, short-term jump in stock prices.

Earlier this month, Pfizer increased its estimate for stock repurchases this year to between $7 billion and $9 billion — essentially spending in one year nearly all of the money it set aside in February for multiyear buybacks. There has been a steady drumbeat of other companies laying off workers even as they have disclosed plans to buy back more stock. On June 23, Campbell Soup said it would buy back $1 billion in stock; five days later it announced plans to eliminate 770 jobs. Hewlett-Packard announced a $10 billion stock repurchase in July, and jettisoned 500 jobs in September after it discontinued its TouchPad and smartphone product lines.

Last month, the first layoffs began at Zimmer’s plant in Statesville, N.C., which is due to shut early next year. The company made splints and tourniquets there for more than three decades. For the sewing machine operators and the rest of the 124 workers at the plant, it is bad news, but it is a different story for Zimmer’s top executives.

Powered by huge stock buybacks — the company bought $500 million worth of its own shares last year, more than twice what it spent on research and development — Zimmer posted earnings growth of 10 percent a share, even though operating income and revenue grew by less than 5 percent in 2010.

That helped its senior management, including the chief executive, David C. Dvorak, collect millions in cash and stock incentive payments by meeting earnings-per-share goals. For example, 50 percent of Mr. Dvorak’s $1.03 million cash bonus was tied to achieving per-share earnings of $4.28 in 2010. The company earned $4.33, but without the share repurchases the company would have made $4 to $4.10 a share.

Investors have not rewarded the strategy, however: Zimmer’s shares have dropped 32 percent in the last five years, while Pfizer’s are down 30 percent in the same period.