We develop a model of advertising markets in an environment where consumers may switch (or “multi-home”) across publishers. Consumer switching generates inefficiency in the process of matching advertisers to consumers, because advertisers may not reach some consumers and may impress others...

We measure the effectiveness of competitive advertising on brand search using alarge-scale, quasi-experimental ad allocation on Bing. Competitors are able to stealtraffic from the focal brand, and they steal an order of magnitude more clicks if the focalbrand's link is exogenously removed from...

We study targeted information in a duopoly model with differentiated products, allowing for consumers with limited attention. The presence of inattentive consumers incentivizes firms to behave as if they were mass-advertisers, despite their ability to direct their messages precisely towards...