It would be an exaggeration to say the European Central Bank shocked investors on Thursday. For long enough they have been expecting the bank to wheel out extra monetary stimulus for the juddering Euroland economy. But they were certainly taken aback when the EBC president Mario Draghi dropped the heaviest possible hints that there could be a big announcement in December, saying the governing council is "willing and able to act by using all the instruments available within its mandate". The inference was that he was talking about more asset purchases (quantitative easing) and possibly sub-zero interest rates.

Sig. Draghi's words sent the euro a swift 2% lower against sterling. Its losses on the week are of a similar scale: the euro is down by two and three quarter US cents and by two and three quarter cents against the pound.