As of March 15, 2020, bank cash reserve requirement was reduced to zero for all depository institutions.[0]
0 - https://www.federalreserve.gov/monetarypolicy/reservereq.htm
0 - https://www.federalreserve.gov/monetarypolicy/reservereq.htm
The fed, fdic and occ all regulate banks capital and have strict requirements around it. Not to mention their equity holders.