Ellis spent his career in the online ad network business, previously serving as the COO of marketing network Webxu.

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Another purchase option is Right Media, an online ad network that has hosted since 2003 an open ad exchange similar to DoubleClick's offering.

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In theory, Walrath's concerns should also apply to any online ad network--if a major player acquires it, that could scare off participation from its rivals.

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The company brokers online ad sales for a large network of buyers and sellers, and as the Web has hit its stride as a marketing vehicle, DoubleClick has become increasingly valuable.

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No one is disputing that Google--which offers a whole suite of tools to publishers to help them make money online, including its AdSense ad network and its new One Pass subscription system--is sincere about wanting to strengthen the news business.

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"Now that DoubleClick has lost its independence, it's an uncomfortable feeling, " says Andy Mitchell, managing director of AdLINK, a British online advertising network that has used DoubleClick's ad service.

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Microsoft could use the company's advertiser network and ad management software to rescue its lagging online ad revenue.

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