I think it's kind of the reverse. Stocks should sell at risk-adjusted rate-of-return parity with bonds. If inflation is 1% (and is expected to stay there), then what's $1 of corporate profit worth? $100 (same as $1 of bond interest would cost). So the stock market has soared because interest rates have fallen. Money has moved into the stock market, seeking rates of return, and has continued to do so until the rate of return of stocks was not higher than the rate of return of bonds.