Craigslist's assault on eBay continued in May. The two sites had equal amounts of unique visitors in the U.S. for the first time ever, according to comScore data.

Citi analyst Mark Mahaney put out a massive report on Internet stocks today, and this chart showing eBay's tanking traffic jumped out at us. Mahaney says, "these long-term very negative traffic trends point to the possibility of sustained eBay U.S. Marketplace underperformance going forward."

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