An eBay seller is looking to cash in on the saga of Samuel Israel, the 48-year-old hedge fund manager whose disappearance Monday sparked a manhunt by federal authorities.

A unidentified seller from Islip, N.Y., put what he claims to be Israel's business card up for auction on the Web site, calling for buyers to "bid for a piece of history."

The card is from the Bayou Group, a hedge fund Israel helped...