Final answer:
Bank capital is the net worth of a bank and a bank must have positive net worth to avoid insolvency or bankruptcy.
Step-by-step explanation:
Bank capital is the difference between a bank's assets and its liabilities. In other words, it is a bank's net worth. A bank must have positive net worth; otherwise it is insolvent or bankrupt, meaning it would not have enough assets to pay back its liabilities. Regulation requires that banks maintain a minimum net worth, usually expressed as a percent of their assets, to protect their depositors and other creditors.