It was early in March 2007 that I realised that two of the world's markets held each other in a tight and deadly embrace.

A week earlier, global stock markets had suffered the “Shanghai Surprise”, when a 9 per cent fall on the Shanghai stock exchange led to a day of global turmoil. That afternoon on Wall Street, the Dow Jones Industrial Average dropped by 2 per cent in a matter of seconds. A long era of unnatural calm for markets was over.

Watching from the FT's New York newsroom, I tried to make sense of it. Stocks were rising again, but people were jittery. Currency markets were in upheaval. In what was becoming a nervous tic, I checked the Bloomberg terminal. One screen showed minute-by-minute action in the S&P 500, the main index of the US stock market. Then I called up a minute-by-minute chart of the exchange rate of the Japanese yen against the US dollar. At first I thought I had mistyped. The chart was identical to the S&P.