A firm commitment is a promise to take a designated action within a specified period of time. The concept most commonly applies to a securities offering, where the underwriter commits to buy all unsold securities. Thus, the underwriter will purchase any remaining portion of the issuance that cannot be placed with investors. This commitment transfers the risk of not selling securities from the issuer to the underwriter. The term can also refer to a guarantee by a lending institution to issue a loan to a borrower within a fixed period of time, if the loan is requested by the borrower.