Madrid SE CATS (MSE) .MC was the Computer Assisted Trading System (CATS) implemented in the Madrid Stock Exchange (MSE) in 1989 and used until 1995. The MSE initially traded seven large-cap stocks on the system and expanded to 51 by the end of the year.


The CATS developed by the Toronto Stock Exchange was the first ever automated market system introduced into a stock exchange. It is credited with being the first system to allow automation of the price-setting process in a centralized, order-driven stock market. It works by the CATS screen showing the size and price of each order entered into the market as well as the intermediary (broker) placing the order; each buy order is then matched by a corresponding sell order in amount and price, and automatically executed. Trade confirmations would then be sent to both the buying and selling brokers, and a record maintained for the clearing system. It was thus much more efficient than the open-outcry system. Another advantage of CATS is that because it records all the trades, it is a repository of a vast amount of useful market information and data.

The CATS system was implemented in a number of other bourses in the 1980s in both developed and emerging markets, including Madrid in 1989. The Madrid Stock Exchange had recently undergone a significant transformation following new laws and the establishment of stockbroking firms and agencies, and the adoption of CATS was part of this process of transformation.

By 1995, the Madrid Stock Exchange had replaced CATS with the more modern Sistema de Interconexión Bursátil Español (the Spanish Stock Market Interconnection System), or SIBE, an electronic trading system developed by the MSE. SIBE connects the four Spanish stock exchanges (Madrid, Valencia, Bilbao and Barcelona) to form a unified, continuous market, providing price information and other data in real time.