Cash flow risk refers to the risk that investors can't raise funds in time to meet the margin requirements for maintaining the stock index future positions. If the price changes unfavorably in the position holding stage, the position loss will increase and the fund balance will be greatly reduced, which may lead to the problem that the remaining funds cannot maintain the current position. According to the requirements of the system of non-liability settlement on the same day, if the insufficient margin cannot be recovered on time on the next trading day, the position it holds will face the risk of being forced to close. This puts very high demands on investors' fund management. In other words, investors must have convenient and fast financing channels to raise funds in a short period of time and meet the margin requirements when the price changes adversely at any time. Otherwise, even if the market judgment is accurate, it may have been "cleared" and there is no chance to "turn over" before it has produced "fruitful results".

If investors conduct Man Cang or heavy positions before increasing the margin ratio, they will face the risk of being forced to close their accounts due to insufficient funds after increasing the margin ratio.