MARK-TO-MARKET – A process whereby the carrying value of a security is adjusted to reflect its current market value.  Certain regulatory requirements mandate that broker-dealers carry positions at prices that reflect current market values.  Issuers or their agents also must generally adjust the value of securities held in a debt service reserve fund or other bond-related fund, or of investments held in a local government investment pool, to reflect current market value.  See:  WRITE-DOWN.