In most cases, a negative USD balance is due to a failed ACH deposit. Because funds are made immediately available for trading in the app, a returned or denied ACH deposit will result in a debit to your USD balance. The most common reason for an ACH return is insufficient funds. Please note that the debit to your bank account may not post for several days, so be sure your available bank balance remains sufficient for at least 5 days after making a deposit to your Voyager account.