Online advertising company ValueClick Inc. said Monday that it has agreed to buy privately held Web shopping site owner MeziMedia Inc., which operates comparison shopping Web sites.

Westlake Village-based ValueClick is buying MeziMedia for $100 million in cash, with the potential to pay up to $352 million depending on the company's revenue performance through 2009.

ValueClick said the acquisition will help boost its presence in the U.S. comparison shopping market. ValueClick already offers comparison shopping in Europe under the PriceRunner brand.

The deal also will give ValueClick a presence in China, as Los Angeles-based MeziMedia has an engineering and operations center in Shanghai and recently launched comparison shopping Web sites in China.

The deal is expected to close next month. MeziMedia has about 160 employees and had $40 million in sales last year.

Shares in ValueClick lost 52 cents, or 1.8 percent, to $29.15 in afternoon trading Monday on the Nasdaq.