Whilst the vast majority of investors expected the Federal Reserve to keep the target range for its benchmark interest rate unchanged at 0.25% - 0.50% there was an outside chance that it would move it higher. It did not happen, and no move is guaranteed before the end of the year, so the dollar moved off its highs, eventually adding no more than half a cent against the euro.
A different uncertainty handicapped sterling as the Brexit threat broke cover again. At the end of last week the idea of a "hard Brexit" gained traction, to which the chancellor added credence when he admitted that the UK is unlikely to remain within the single market. Although it was purely speculation, investors were reminded that even three months after the vote nobody has a clue how it will all work out for Britain. That uncertainty cost the pound two US cents.