Mark-to-market

The process of determining the present market value of a security, a derivative position or a portfolio by reference to the most recent price at which a financial instrument can be bought or sold in normal volumes. The mark-to-market value might equal the current market value-as opposed to historic accounting or book value-or the present value of expected future cash flows.
Stock-exchange: The process by which contracts are revalued each day for the calculation of variation margin.