The companies want to make online shopping more convenient by pairing offerings from MSN with eBay. There will be further integration between the two sites later in the year.
The deal also sees eBay's advertising appearing across the MSN network in relevant places.
Richard Bray, vice-president of the MSN US region, said: "Shopping is an incredibly popular online activity, and eBay is consistently one of the top five search queries on MSN Search. By integrating the eBay marketplace more deeply throughout the MSN network, we will provide consumers with an even more useful, complete and convenient online experience."
EBay and MSN already have an agreement whereby "outbid" and "auction ending" alerts for online auctions are sent to eBay users using the Microsoft.NET Alerts platform.
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