Another sharp sell-off on US equity markets saw 'level 1 market-wide circuit breakers' triggered after the S&P500 opened the session down -7% (and resulting in a 15-minute trading halt), with further sharp falls in oil prices sowing further concerns - Dow tumbled -2014-points or -7.79% to record its worst single session performance since 15 October 2008 (when the index fell -8.7%). Boeing Co fell -13.4% to its lowest levels since 2017 after the US Federal Aviation Authority (FAA) said it did not agree with the planemaker’s decree that its 737 MAX wiring bundles met safety standards. Separately, Ethiopian investigators singled out faulty 737 Max systems in a new interim report on last year’s fatal crash. Boeing Co, Apple Inc (down -7.91%), Goldman Sachs Inc (-10.39%) and Caterpillar Inc (-14.28%) cut the index by at least 100 points each. The broader S&P500 -7.6% to 2,746.56, logging its worst single trading day since 1 December, 2008. J.P. Morgan Chase and Co (down -13.55%) and Bank of America Corporation (down -14.7%) were under particular pressure among the banks as they are among the biggest lenders to the energy sector. For those of a technical bent, the closing level represents the 61.8% Fibonacci retracement level. The 61.8% retracement of the S&P 500's rally off the 24 December, 2018 closing low of 2,351.10 to the 19 February, 2020 record close of 3,386.15 comes in at 2,746.49. Many chart watchers believe a convincing close below that level would suggest a full retracement of the previous rally becomes the next downside target. The NASDAQ -7.29%.