Optimism over growth, a buoyant property market and surging retail sales have failed to spur on the index of London's leading shares after it surged close to an all-time high earlier in the year.
Traders are instead looking ahead to what might happen if prospects continue to improve - and are fearful about what they see.
The index of London's leading shares reached 6682 at the close on August 1 but was more than 200 points lower at 6453.5 at the end of yesterday's session, representing a drop in value of £58.4 bn for the month so far.
In May, the FTSE 100 had reached 6840.3, its best result since the dotcom boom in December 1999.
Even now, the index is still nearly 1000 points above its level last summer.
Markets have been propped up by massive asset purchase programmes - or quantitative easing - by central banks leaving many anxious about what will happen when this is taken away. There are increasing expectations the US Federal Reserve will begin to "taper" its QE from next month.
It means that better-than-expected economic data from the world's largest economy may perversely be received with dread because it increases the likelihood that policymakers will see less of a reason to keep monetary stimulus in place.
Quickening growth in the US and the end of the recession in the eurozone have not been as welcomed as might be expected.