What was the catalyst?
US equities are down almost 10% this month but despite waves of risk aversion, the US dollar hasn't performed as strongly as you would expect.
"This likely reflects a number of factors, including long Dollar positioning and, by the end of this week, some modest repricing of Fed expectations," Goldman Sachs writes in a note today.
They argue another factor is bubbling below the surface, a fall in US growth expectations. Based on historical sensitivity to the S&P 500, they argue that the US dollar should have risen about 1.5% rather than the 1% gain it's experienced.
Moreso, they argue that globally-sensitive currencies like the New Zealand and Australian dollar have held up far better than expected while US-linked economies like Canada, Mexico and Colombia have struggled.
I'd argue there's a bit of cherry picking here as the USD performance looks much more uniform if you include the first few days of October. The loonie was also hit by some soft data.
That said, it's an interesting perspective.