ValueClick has promoted Tom Vadnais, currently its president of U.S. operations, to CEO, succeeding James Zarley, who headed the digital ad shop since 1999. Zarley remains as executive chairman of the board of directors. Release.

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ValueClick is considered by some to be a hot acquisition target, especially in the wake of the purchase of former independents aQuantive, 24/7 Real Media and Digitas. One analyst, Global Crown Capital’s Martin Pyykkonen estimated ValueClick’s potential sale price could rise as high as $4 billion. But as we recently noted, some analysts are dismissive about ValueClick’s promise because buyers are more interested in gaining ad serving technology, which apparently only makes up a small part of the company’s sales. ValueClick’s main focus is on its response-driven placements across thousands of small and midsize websites, and a lead-generation business.