Chiron Corp., the third-largest U.S. biotechnology firm, said Chief Financial Officer James Sulat will resign.
Sulat, 55, will leave the Emeryville, Calif.-based firm next month "to pursue other opportunities," spokesman John Gallagher said, without giving details.
Chiron, which sells vaccines, blood tests and drugs, hired GlaxoSmithKline executive Howard Pien last month to take over as chief executive, succeeding Sean Lance.
David Smith, 43, vice president of finance, will take over the post on an interim basis.
Chiron shares fell 41 cents to $39.48 in Nasdaq trading.