Real rate is different from interest rate. Real rate is the difference between interest rate with the inflation. We have been running on negative real rate for a decade plus. This is an accommodative measure by the Fed to make sure the market is still running hot. S&P500 has been running well during this period of time where the interest rate is kept below the inflation. However there are several occasion where the negative real rate is running deep in 1970s and 2020s, which prompt the Fed to raise the rate. However so far we have not seen real rate hikes goes into positive territory yet. When the real rate is in positive territory S&P500 index will also running well as the economy is running well without Fed's life line support. However I'd expect that the market will be flat and volatile during transition between negative to positive real rate, because the market trying to figure out whether the economy would be running well or not when the life support is removed slowly.