Watson Pharmaceuticals

(WPI)

said Thursday that Fred Wilkinson, its operating chief and senior vice president of sales and marketing, has resigned to become chief executive and president of

Columbia Laboratories

(COB)

.

Shares of Watson, which is based in Corona, Calif., fell $2.32, or 4.3%, to $51.28 in regular-session

New York Stock Exchange

trading. Shares of Columbia rose 15 cents, or 2.8%, to $5.60.

In February, Watson said it

beat Wall Street's earnings expectations for the fourth quarter, but slumped from the year-ago period.