Seth Merrin

Grew up wealthy on New York's Upper West Side; father owned a gallery that sold ancient art. Applied for jobs waiting tables after studying at Tufts; restaurants said he wasn't qualified. Founded Merrin Financial: made brokers' lives easier with electronic order-management software. Sold for $23 million to ADP in 1996. Created Liquidnet; "dark pool" allows institutional investors to trade large blocks of securities without wild swings in prices. Sales up 115% since 2005 to$350 million. Public offering imminent.