Total liabilities is the sum of your Short Market Value plus your Debit Balances from the prior trading day. Short Market Value is the market value of short positions held in your short account as of the prior day's market close. Increases in this figure mean that positions you have sold short are moving against you, or up. Each Monday, your short account will be marked to the market. The Short Market Value of the account is used to recalculate the proper level of collateralization to secure the short positions in the account. The Debit Balance reflects the closing debit balance as of the close on the prior trading day.