The Chicago Board Options Exchange's Hybrid Trading System (HyTS),  launched in 2003, is a trading system that combines features of open outcry and electronic trading mechanisms. CBOE, unlike a number of newer U.S. options exchanges that began as solely electronic marketplaces, originally began as an open outcry trading options model.
Hybrid was the culmination of a three-year systems project to meld the efficiencies of electronic trading with the depth of liquidity and price discovery of the trading floor. It takes into account the factor of human intellect in transacting more complex options orders.
CBOEdirect, is the trading engine of the Hybrid Trading System.
For trading desks, the CBOE's HyTS Terminal (Hybrid Trading System)  is a multifunctional trading solution workstation using point-and-click functionality. It offers users connectivity to CBOE and all other U.S. options exchanges and multiple stock and futures exchanges. Additionally, HyTS makes available complete access to options market data, streaming quotes and order management, all on a single screen.
In July 2004, Hybrid 2.0 (or H2O) enhancements were put into place at CBOE. This introduced electronic Designated Primary Market Makers (e-DPMs), expanding the benefits of the Hybrid Trading System by adding additional liquidity and depth to CBOE's markets.
In April 2005, CBOE introduced Remote market makers (RMMs), a new class of CBOE membership designed to allow individual market makers and member organizations to engage in market making at CBOE from any location.
The Remote market maker and e-DPM designations have enabled a wider range of market participants to access the trading system.