Styron, a $3.7 billion plastics company spun off by Dow Chemical earlier this year, named Richard Diemer Jr. CFO and executive vice president, John Sereda treasurer and vice president, and George Osborne controller and vice president. Diemer, 52, replaces Celso Goncalves, who is leaving at year-end. Diemer had been the CFO of Albemarle Corp. since 2005. Prior to that, he was corporate controller of Honeywell International. Sereda most recently was treasurer and vice president of finance at Nova Chemicals. Osborne was Dow's director of M&A.

Bally Technologies, a $778 million gaming company, promoted Neil Davidson to CFO, corporate treasurer and senior vice president. He replaces Robert Caller, who is retiring as CFO, but will remain with the Las Vegas-based company under a long-term consulting agreement. Davidson, 37, most recently served as Bally's chief accounting officer. Before joining Bally in 2006, he was vice president of finance for Multimedia Games, a gaming and systems company. Davidson began his career at KPMG.

PMA Capital, a $531 million insurance company, promoted John Cochrane to CFO and senior vice president. He had been interim CFO since December, when William Hitselberger left to join Tower Group. Cochrane, 55, most recently was senior vice president of finance. Prior to joining Blue Bell, Pa.-based PMA in 2003, Cochrane held various roles at insurance companies. He began his career at Peat Marwick Mitchell & Co.