Also known as fair value or MTM accounting. In the context of accountancy, a method of accounting whereby the company's balance sheet shows loans and debt instruments at their fair value, which may be higher or lower than cost. Any profits or losses due to any change in value will go to the profit and loss account or to reserves. Only certain types of companies can use mark to market to account for any loans and debt instruments. These will mostly be banks, insurance companies and investment funds.

In the context of valuing an investment (for example, a derivative transaction or a loan evidenced by a bond), the revaluation of the investment to its current market value.

For further details, see Practice note, UK MMF Regulation.