At 9:35 a.m., 8 of the 11 S&P 500 sectors were up.
By 11:40 a.m., none were.
Staples and energy held out the longest. Tech, industrials and consumer discretionary never saw green.
All 11 closed down. The S&P 500 fell 4.4%, and chip stocks fell 12.2%, their second-worst day since 1994.