they're big in single name option market making. one of the largest i think.
Timber Hill, IB and Thomas Peterffy are an amazing story.
You can read about his back ground and how the firm started here:
http://www.iinews.com/site/pdfs/IIMag_InteractiveBrokers_Nov_2005.pdf
In 1982 he reorganized T.P. & Co. into a new firm, named Timber Hill after two roads in a favorite upstate New York retreat. Timber Hill became both a vehicle for Peterffy’s own trading activities and a laboratory for bringing his vision of efficiency to the wider market. He hired several other traders and designed handheld computers to help them continuously determine the fair value of options. The goal: to use the handhelds for making markets on the Amex and then expand to the CBOE, the biggest U.S. options exchange at the time.
Timber Hill’s early years were anything but an unmitigated success. It had to overcome resistance from exchange officials and fellow floor traders. Peterffy was able to persuade the Amex that his devices would benefit the market, and the exchange permitted him to bring them onto the floor in November 1983. At the CBOE, however, he encountered stiff opposition: A committee ruled that Peterffy’s box, which measured about 12 inches long by nine inches wide and a few inches deep, was too big to use in the tightly packed trading crowd. Though astonished that CBOE members didn’t appreciate the benefits of his system, Peterffy went back and redesigned it to be about the size of a child’s lunch box. (He keeps some of the old devices in a display case in his office.) After a second hearing the CBOE panel abandoned its size objection and cut to the heart of the matter, ruling that no analytical devices could be used in the pits. “It caused a brouhaha,” recalls a former CBOE trader. “People got kind of hysterical at the idea of changing the rules.” Recalls Lehman vice chairman Russo, who was then a partner at New York law firm Cadwalader, Wickersham & Taft and represented Peterffy in his battles, “It was obviously a case of people fearing innovation. Tom had his vision, and he wanted to implement it, but they were afraid that this new technology would change their world too much.” Peterffy scuffled through the next few years, occasionally wondering whether his embryonic market-making business could survive the setback. His business plan depended on earning enough from trading with the first generation of handhelds to pay for exchange-seat leases and to invest in a more sophisticated system. Blocked by the CBOE, he sought to do business on other trading floors. In 1985 the fledgling options division of the New York Stock Exchange permitted Peterffy to deploy his technology, hoping that it would attract liquidity from its bigger rival in Chicago. But exchange officials insisted that the devices could be used only at trading booths located as much as 30 feet from the crowd where transactions were executed. To overcome this problem, Peterffy developed a code system in which Timber Hill personnel using computers at the booths flashed messages using colored lights, each representing a number from zero to nine, to their colleagues in the pits. It took traders about two days to learn the system, after which they could read the light display as readily as the digits on a computer screen. This quickly caused a stir among other traders...
