There are lot's of people claiming that an expansion of the balance sheet ( M1 ) does not lead to an inflation of the monetary supply ( M2 ) since the additional reserves created by the Fed can't be spent by the primary banks that receive them. This does not take into account the fact that there being less debt instruments after the purchase (yet the same amount of currency) will create appetite in the market for companies to issue new debt, leading to an expansion of M2. Additionally, in the future the primary banks could use those increased reserves to lend more money into the market if/once the appetite for borrowing increases and interest rates increase. To see whether there's a correlation we compare M1 (e.g. cash & reserves) with M2-M1 (broad money supply minus cash & reserves).