1. In banking, it is the incapacity of a bank to honor its repayment commitments to other banks. In inter-bank fund transfer systems this inability can cause catastrophic cascading failure of several or all banks associated with the transaction. 2. In securities trading, it is the situation where on the settlement date either a seller is unable to deliver the contracted securities (called a short fail) or the buyer is unable to pay for them (called a long fail).