Assets are not limited to cash.

The full name of stock index futures (SPIF) is stock index futures, which can also be called stock index futures and futures index. It refers to the standardized futures contract with the stock price index as the subject matter. The two parties agree to buy and sell the underlying index according to the size of the stock price index determined in advance at a future date, and settle the difference in cash after the expiration. As a type of futures trading, stock index futures trading has basically the same characteristics and processes as ordinary commodity futures trading. Stock index futures are a kind of futures, which can be roughly divided into two categories, commodity futures and financial futures.