After a long period of calm, investors get a shock.
Every good horror-film director knows the secret of the “jump scare”.
Just when the hero or heroine feels safe, the monster appears from nowhere to startle them.
The latest stockmarket shock could have been directed by Alfred Hitchcock.
The sharp falls that took place on February 2nd and 5th followed a long period where the only direction for share prices appeared to be upwards.
In fact the American market had risen so far, so fast that the decline only took share prices back to where they were at the start of the year.
And although a 1,175-point fall in the DowJones Industrial Average on February 5th was the biggest ever in absolute terms,
it was still smallish beer in proportionateterms, at just 4.6%.
The 508-point fall in the Dow in October 1987 knocked nearly 23% off the market.
Still, surprise rippled round the world.
Between January 29th and early trading on February 7th, the MSCI Emerging Markets Index dropped by 7.5%.
The FTSE 100 index fell by 8.2% from its record high, set in January.
A late recovery on February 6th, in which the Dow rebounded by 2.3% (or 567 points), restored some calm.