Cotation Assistée en Continu (CAC) was an electronic trading system used at the Paris Bourse, the French stock exchange, in the 1980s and 1990s.
The acronym is also used to refer to the CAC 40, a stock index provided by the Paris Bourse.
Curiously, the acronym also fits the name of the early Parisian stockbrokers' association, the "Compagnie des Agents de Change".
In the early 1990s, the Paris Bourse developed an upgraded technology known as Nouveau Système de Cotations|NSC (Nouveau Système de Cotation), which served as a technological platform for the Euronext initiative.
CAC, like CATS, was an order-driven market platform that handled the process of order matching and price setting through a double auction algorithm.