The dollar rose in afternoon trading as the stock market tanked on worries about the economy and fears that Federal Chairman Ben Bernanke will not lay out any further plans on Friday by the central bank to support markets and growth.
Announcing a new round of bond-buying could drive down interest rates, which can boost growth. But lower rates weigh on a currency.
Last year, when Bernanke announced supportive measures for the U.S. economy at an annual economics conference in Jackson Hole, Wyo., the dollar dropped sharply.
The dollar is rising now because investors are thinking that Bernanke won't signal additional aid from the Fed, despite the slow economic growth in the U.S., said Forex.com currency strategist Brian Dolan.
In New York Thursday, the euro dropped to $1.4368 from $1.4421, the British pound fell to $1.6281 from $1.6374, while the dollar jumped to 77.55 Japanese yen from 77.01 yen.
The dollar fell to 0.7939 Swiss franc from 0.7947 franc. It was practically unchanged at 98.82 Canadian cents from 98.83 Canadian cents.