The Fed model is used by Wall Street sales desks as it almost always gives a "buy signal", and has rarely signaled stocks are overvalued. Some academics say the relationship, when it appears, is driven by the allocation of the Fed's balance sheet to Wall Street banks via repurchase agreements as part of Fed put stimulus (i.e. the relationship reflects the investment strategy that these banks follow using borrowed Fed funds, e.g. Wall Street banks lending to Long-Term Capital Management-type vehicles during the 1990s being a noted example).