UDN is more of a bet against the dollar than a bet on any particular currency. It shorts USDX contracts, which means that it's shorting the US dollar and long six G10 currencies: the euro, Japanese yen, British pound, Swedish krona, Canadian dollar and Swiss franc. The USDX uses a fixed weighting scheme based on exchange rates in 1973 that heavily weights the euro. As a result, expect to see big moves in the fund in response to euro movements. Structured as a commodities pool, UDN distributes K-1s and is marked-to-market at year-end.