In 1976, Ritchie started working the floor of the Chicago Board Options Exchange (CBOE). Ritchie's time at the CBOE lasted a short two months, but it was there that he programmed the Black–Scholes formula into his Texas Instruments SR-52. This small use of technology led to a huge success on the floor. Ritchie later lost interest in trading stock options, and left the CBOE, but before he left, he gave his Texas Instrument calculator, which was programmed with the Black–Scholes formula, to Steve Fossett.