Traders are glued to a key level on the charts

US stock markets on Wednesday faced their worst sell-off since February.
Traders are paying close attention to key technical levels, and right now the 200-day moving average is in focus.
The S&P 500's 200-day moving average has been tested three times this year, and has so far managed to hold.
The Nasdaq has already plunged below the technical level for first time since June 2016.US stock markets witnessed their heaviest selling since February on Wednesday, with all of the major average