The negative balance of available margin means that when investors buy and sell new wealth management products, the remaining margin in their accounts is not enough to pay the required margin for these new wealth management products, so investors need to replenish the margin in time, otherwise investors will not only be unable to buy these new wealth management products, but also the products they already hold will explode. Margin means that investors deposit some funds into financial institutions in order to handle some financial business. As the guarantee for investors to fulfill certain obligations, it can be divided into seven types: the deposit without double return effect, the deposit with return right, the decoration deposit, the deposit, the lease deposit, the advance payment and the reserve.