What happened
US financial regulators have loosened a key capital rule for the largest banks. This means banks can hold less cash against certain low-risk assets, making it cheaper for them to participate in activities like government bond markets.
Why it matters
The largest US banks, known as global systemically important banks, have to keep a certain amount of cash in reserve. This rule, called the supplementary leverage ratio, was meant to be a backstop, but it sometimes limited banks from holding low-risk assets like US Treasury bonds. Now, banks can hold more of these assets without triggering the rule, which could make it easier for them to act as market makers for government debt.