Fairly new at this and don't work in the sector, just someone who enjoys this stuff. I think it's because if the banks have too much cash, that's expensive bec

Fairly new at this and don't work in the sector, just someone who enjoys this stuff. I think it's because if the banks have too much cash, that's expensive because it depreciates. They don't want just "mattress money", so when too many people deposit and not enough people withdraw, banks have too much cash, and need a place to park it. If they can't park it anywhere, that means that they don't want more cash, which pushes the interest rates down. Fed has decided that interest rates going down is bad, so they basically say "hey, we'll take the cash off your books, give you a small interest payment for buying the treasuries" and now the banks don't mind taking more cash in. Basically this is a way of keeping the interest rates higher on deposits, because the banks get subsidized to use that cash to borrow Treasuries, this gets unwound every night. So the banks can operate like they don't have too many deposit liabilities, even though they would without reverse repo. I think this is a defense against inflation: If banks can't earn anything from cash, that means they have to push out more loans. Loans add risk/leverage (because it's that money creating event) and they also serve to increase monetary supply, causing inflation. Fed has decided that they'd rather control this process instead of leaving it to the free market in hopes that the situation returns to normal instead of causing additional inflation. This could be just kicking the can down the road, but what do I know.