Jonathan Wittmann leaves the exchange after six years in one of the most high-profile IT jobs in the UK.
A spokesman for the exchange declined to comment on whether Wittmann had moved to another company. Last year David Lester was appointed chief information officer. The reshuffle comes as the London exchange remodels itself as a technology consultancy, selling its proprietary trading platform, Sets, to other exchanges.
Since 1996 Wittmann has presided over some turbulent times, including the abortive merger bid with the Frankfurt stock exchange in 2000 and seeing off a hostile takeover bid from Swedish exchange and technology supplier OM Group.