There is no cycle for bank B there. It went from Bank B $1m deposit [$100k required reserves + $900k excess reserves] to Bank B $1m deposit with 900k

There is no cycle for bank B there. It went from Bank B $1m deposit [$100k required reserves + $900k excess reserves] to Bank B $1m deposit with 900k loan (90%) [$100k required reserves + zero excess reserves] and it's still there at the end. It doesn't have excess reserves, it cannot make new loans if it cannot get more money. To be clear, my original comment was: "The money created doesn’t necessarily go back to the bank. When you take a loan you use the money for something, not to keep it in an account at that bank. It will typically end in another bank." The bank =/= A bank One bank =/= The banking system [Of course when another bank gets more reserves it increases their capacity to extend new loans. The question was whether a bank with $1m in deposits can lend $9m, not whether the whole banking system could.]