The 1980s saw the advent of Program Trading, a computerized type of securities trading involving a number of different portfolio trading strategies, where there was a purchase or sale of a basket of securities having at least fifteen stocks, valued
above $1 million total. Program trading gained popularity for trades between the S&P 500 equity shares and the futures market, such that a program could automatically put in an order in the NYSE’s electronic system when there was a predetermined difference between the two markets.