MOUNTAIN VIEW, Calif.--Google's top executives on Thursday gave a glimpse into how it might try to deflect antitrust concerns of a possible ad-sharing deal with rival Yahoo, advising observers to look at the overall ad market.

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With all the talk about creative destruction and competition, technology keeps creating monopolies: General Electric ( electric machines and distribution); ATT ( phone networks); IBM ( business computers); Microsoft ( PC OS and office software); Google ( web advertisement).