A debit balance in a margin account is the amount of money a brokerage customer owes their broker after borrowing funds to purchase securities on margin. When buying on margin, investors borrow funds from a broker to purchase a greater number of shares. The adjusted debit balance tells the investor how much they would owe the broker in the event of a margin call. Brokers charge interest on the money they lend. A special memorandum account (SMA) is set up in conjunction with a margin account to hold excess margin. A margin call occurs when the customer's account falls below the brokerage firm's minimum maintenance requirement. 624a