Besides arbitrage between futures and the underlying cash market, it is also done between contract months of a futures contract and between different futures products. When the actual price of equity index futures is above the theoretical price, selling the futures and buying the underlying stocks is called cash-and-carry arbitrage (kai-saitei in Japanese). When the futures price is below the theoretical price, buying the futures and selling the stocks is called reverse cash-and-carry arbitrage (uri-saitei).