Financial Market Utilities (FMUs) are entities, outlined by Title VIII of the Dodd-Frank Act, that clear and settle payments, securities, or other financial transactions between financial institutions. They are considered to be critical infrastructure for the financial system. Title VIII established a a regulatory and supervisory regime to overseee FMUs, where it designates "systemically important" utilities.
The Financial Stability Oversight Council (FSOC) determines which FMUs are systemically important. Though, the Federal Reserve is ultimately charged with developing and enforcing the prudential standards for systemically important FMUs. Title VIII also gives systemically important FMUs access to the discount window, where the institutions can take out loans at near-zero rates. 
- Financial Market Utilities. Economics of Contempt.