Amazon announced a deal today to acquire apparel and footwear retailer Zappos.com. The popular online retailer ranked 3rd last week among online retailers within the Apparel and Accessories category behind Victoria’s Secret and Old Navy. Both Amazon and Zappos.com are well-known for the breadth of product offerings, so it is not surprising that they share much of their audiences. For example, last week, Zappos.com was the top visited Apparel & Accessories website following a visit to Amazon and of those visitors, 79% had visited Amazon within the past 30 days. The chart below is filtered to include only websites from the Apparel & Accessories category.

Amazon delivered more traffic to Zappos.com than one of its own properties, Endless.com, which also sells footwear & accessories (with very little tying it to Amazon until an actual purchase), which has been the case for the majority of weeks over the past year.

The shared traffic combined with the size and reach of both websites also results in a similar audience composition, particularly by age and household income. The chart below displays the top 5 retailers, filtered to include only the Apparel & Accessories category, ranked by the similarity of their demographic profiles to Amazon. The closer the score is to 1, the more alike the demo profile.

Age is a good example where the audiences are very similar, but subtle differences do exist. Amazon attracted a higher share of visitors between the ages of 18 and 34 than Zappos.com over the past 4 weeks. Conversely, visitors to Zappos.com were slightly older, so there could be growth opportunities for both of the websites.

For now, it looks like business as usual for Zappos.com, so customers may not even realize that ownership has changed hands.