buying behavior. On average, for each US resident, Acxiom keeps about 1500 pieces of
data. Thus, Acxiom has a wealth of information that it can sell to interested parties, in
particular with the aim to better match advertising or services to user tastes.
While on traditional ad-financed media, the user pays with her attention, on Internet
media, the user pays not only with her attention, but also with her personal data. Thus,
websites including Internet media may make revenues even if they neither charge users
nor carry any advertising. They can accomplish this by opening a third source of
revenues—selling user information.
A number of theoretical efforts help in understanding the forces at play when media
platforms track users or rely on third-party information in their effort to best match
advertising to users. The model presented at the end of this subsection explicitly includes
the sale of user data for the purpose of targeting.
A media platform may provide tracking information about consumers to advertisers.
Doing so allows advertisers to bid for ads conditional on the information they receive.
When advertising space is scarce, advertisers operating in such an environment internal-
ize that in case of tracking their bids will only be successful if they provide better matches
to consumers than other advertisers; absent tracking advertisers offer similar expected
match quality. As a consequence, advertisers set higher retail prices with tracking infor-
mation than without. While tracking improves average match quality, leading to higher
retail prices and thus larger industry profits, it also reduces the share of industry profits that
can be extracted by the platform, as advertisers set prices prior to learning consumer
types.
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Thus, it is not obvious whether the platform benefits from tracking.
de Cornie
`
re and De Nijs (2014) formalize this tradeoff and investigate the platform’s
incentives to install a tracking technology. Here, through a second-price auction,
a monopoly media platform sells a single advertising slot to n advertisers.
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This slot gives
exclusive access to the consumer. Thus, sellers act as monopolists in the product market.
The timing of the model is as follows: First, the platform decides whether to install a
tracking technology. Second, advertisers simultaneously set the product price p
i
,
i ¼1,…,n. Third, the consumer type is revealed to advertisers under tracking; it remains
unknown otherwise. Fourth, advertisers simultaneously place bids for the advertising slot
conditional on the information they received. The consumer is matched to the winning
advertiser.
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If prices were set conditional on consumer types and thus advertisers customize retail prices, they would
extract a larger fraction of consumer surplus. However, this would drive up bids. Advertisers would be
worse off since the difference between valuation of the winning bid and the valuation of the second
highest bidder (and thus the price in the auction) shrinks when advertisers can customize the retail price
compared to the setting where they cannot.
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Selling a single slot is perhaps the simplest setting and avoids the need to consider alternative multi-unit
auctions. Suppose that advertisers are potential competitors in the market place. Then, it is optimal to sell a
single slot if monopoly profits exceed industry profits with two or more firms.
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The Economics of Internet Media