Commodity demand reflected in futures—and ETF—prices.

The S&P 500 started Tuesday 17% higher than a week ago, after gaining four days out of five and posting its best week since 2009.

The Fed’s pledge last week to buy investment-grade credit and certain ETFs helped halt the slide in mutual fund net-asset values and sparked a rally in higher-rated debt.

The prevailing feature of the recent turbulence is that nothing has really worked as it was supposed to work.