These days, the Dollar and the Yen are veritable proxies for investor confidence/risk tolerance. As a result, on days when US stocks rise, the Dollar (somewhat ironically) will typically experience a decline. Over the last couple weeks, it should therefore come as no surprise that the tremendous rise in US stock prices was matched by a proportional fall in both the Dollar and the Yen. If only for technical reasons (i.e. that the scale tipped too much in the other direction), it seems investors have regained some of their comfort with investing in emerging markets, leading some of the hardest-hit currencies (Korean Won, Brazilian Real, Mexican Peso) to recover some of their gains. Call it wishful thinking, but some investors now believe that the US recession will be milder than originally forecast, which would certainly exert a positive impact on such emerging market economies. In addition, there were monetary factors underlying the currency reversal, reports The Washington Post:

There were more specific reasons for some of the fluctuations. A news report that the Bank of Japan might cut rates in the near future was a factor in driving down the yen.

Read More: Currency Swings Reverse Course