SOFR is based on the U.S. repo market and is considered broad based. This is because the rate is determined from the tri-party repo market, the general collateral financing (GCF) repo market and the bilateral repo market (For more specifics about this rate, calculations and its features go to https://www.gfmi.com/articles/libor-schmibor-whats-next-sofr-part/. It is used as the risk-free reference rate for U.S. cash and derivative instruments.
