As Halloween sweeps in, no shortage of frights haunt investment markets, including the trade war with China, a recession in the manufacturing sector, and unusual U.S. political uncertainty.

Despite the scary possibilities, the worst stock market drops of the past year all followed the Federal Reserve Board's pronouncements, and the Fed has been able to avert the market's worst fears.

For months now, the Federal Reserve, as it works to extend the economic expansion into 2020, has driven the stock market — both up and down.