Stock index futures were introduced in 1982 and have since become the second most significant sector of futures trading, after interest rates. The document discusses the mechanics and pricing of stock index futures contracts, focusing on E-mini contracts. E-mini contracts have more modest contract sizes than traditional stock index futures contracts and are traded exclusively via electronic platforms. The document explains how stock index futures are priced relative to their underlying spot indexes, the concept of cost of carry pricing, and how arbitrage helps enforce cost of carry pricing in stock index futures markets.