There are several different kinds of requirements that banks have. The "reserve requirement ratio" basically means that for every $1000 the bank has in deposit

There are several different kinds of requirements that banks have. The "reserve requirement ratio" basically means that for every $1000 the bank has in deposits, it is required to keep $X in its account with a Federal Reserve bank. Very specifically, it has to be money sitting in that account--a literal stack of $20 bills doesn't count for the reserve requirement. This has dropped to 0% because the Federal Reserve figures there's better ways of maintaining bank solvency. Instead, most attention nowadays is paid on the capital ratio. This basically says that the bank needs to hold $X equity for every $100 of risk-weighted assets. My understanding is a little fuzzy here, but I believe that the equity here is completely separate from what's normally counted as assets for a bank.