answer; the nav calculated at the market close at 4: 00 pm new york time;
Banks loan out all of their excess reserves.
It is virtually impossible for a bank to loan all the money it has (deducting required reserves) since loans are handed out every day and are also repaid every day. It is a constant flow, where clients are constantly getting new loans (or refinancing old loans) or repaying existing loans. The only way that a bank could loan all its available money would be that the bank has only a few clients that simultaneously get large loans, but that would carry huge risks.