Interactive Brokers sold its IPO the way it ran its business: by machine. In May 2007 the Greenwich, Connecticut firm skipped the usual bank-run book and held an online auction, where anyone could bid and every winner paid the same price. The auction settled at $30.01 a share and raised $1.2 billion. Even then, the public bought only about 10 percent of the business. Founder Thomas Peterffy and his team kept the rest.

A Lone Trader on the Amex

Thomas Peterffy started in 1977 as a lone market maker on the American Stock Exchange. His market making firm, Timber Hill, formed in 1982 and leaned on computers to price trades. A brokerage arm, Interactive Brokers, followed and sold the same machinery to outside traders. By the time it filed, the company called itself an automated global electronic market maker and broker. It was a member of more than 60 electronic exchanges and trading venues, handling stocks, futures and foreign exchange.

Forty Million Shares by Auction

The OpenIPO auction, run by W.R. Hambrecht + Co., closed in early May 2007. Interactive Brokers sold 40 million shares at $30.01 each and listed on the Nasdaq Global Select Market as IBKR. The new public company owned about 10 percent of IBG LLC, the holding company for the whole business. Peterffy and the other insiders held the other 90 percent through a holding company of their own. Interactive Brokers still trades on Nasdaq under IBKR.

Cover: The Auction House: The Expert, Charles Maurand. Art Institute of Chicago, public domain. Chosen for an auction house (the OpenIPO auction).