A few short weeks ago the Dow industrials were on the verge of busting through another psychological milestone at 27,000.

However, all that momentum has evaporated as a sweeping downturn grips financial markets, sending the Dow Jones Industrial Average tumbling more than 600 points on Wednesday and pushing the Nasdaq Composite Index into correction territory for the first time since February 11, characterised as a drop of at least 10% from a recent peak.