Summary

• The ASX 200 fell by as much as 2.3% to a five-week low at Wednesday's open 
• Wall Street's mega-cap tech sell-off gathered pace overnight. Amazon gave up 4.4%, Facebook shed 4.1% and Google parent Alphabet fell 3.6%
• The NASDAQ entered correction territory, with the index dropping 4.1%. The Dow Jones fell 2.3% and the S&P 500 lost 2.8%
• AstraZeneca has put a hold on the late-stage trial of its highly-anticipated COVID-19 vaccine candidate after a suspected serious adverse reaction in a study participant