What you are looking at is a chart of POMO activity (Treasury + Agency) that is being expressed as "billions of dollars per day." No effort has been made to account for weekends or holidays; this is simply taking each POMO and dividing it by the number of days that pass until the next one.
Pomo= Permanent Open Market Operations, the purchase or sale of Treasury securities on an outright basis adds or drains reserves available in the banking system
The Fed is openly and actively buying dodgy debt from the government as well as from the private sector. On POMO days the stock markets exhibited some statistically unlikely upward thrusts in the final few minutes of each associated trading day.
Under this scenario POMO money is being shuffled out of the endless thin-air vaults of the Fed and into the banking system where it needs to find something to do. One of those things, it seems, is to goose the stock market, especially late in the day.
Notice that the intiation of the POMOs correspond to the rally,
