The repo market is an important source of funds for large financial institutions in the non-depository banking sector, which has grown to rival the traditional depository banking sector in size. Large institutional investors such as money market mutual funds lend money to financial institutions such as investment banks, either in exchange for (or secured by) collateral, such as Treasury bonds and mortgage-backed securities held by the borrower financial institutions. An estimated $1 trillion per day in collateral value is transacted in the U.S. repo markets.