But the total online ad market still accounts for only a small percentage of overall ad expenditures.

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Mobile ad growth might be an issue, since mobile ads constituted 23% of overall ad revenues, a little shy of forecasts.

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Product placement can be done after filming and content owners will be able to sell placement in every market, probably to different clients, for a potentially more lucrative overall take of ad sales.

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Second, because display ads drive consumers down the funnel so that they click more on search ads and eventually become a customer, this process also increases overall ad cost due to additional search clicks.

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But the business model is unproven, and ad dollars will initially be a fraction of the industry's overall revenue.

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This growth has stayed above overall advertising market growth despite a slight decline in TV viewership, indicating the strengthening of ad pricing.

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The lower cost of Google's mobile ads compared with those viewed on a desktop have contributed to an overall downturn in the average amount paid by advertisers every time someone clicks on an ad, the company has said.

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In the first six months of the year, overall ad spending in the U.S. fell 1.6%, compared with the same period a year earlier, according to data released by TNS, a division of Taylor Nelson Sofres that tracks ad spending across 20 media segments.

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