The IMF data showed the dollar's share of the roughly $4.4 trillion of world reserves of which the composition is known fell to 61.6 percent between July and September, from 62.8 percent in the prior quarter. The euro's share of known reserves edged up to 27.7 percent from 27.4 percent and the yen share rose to 3.2 percent from 3.1 percent, the data showed.

Holdings of "other currencies" -- a reference to currencies other than the dollar, euro, yen, sterling or Swiss franc -- showed the biggest shift. Though a small share of the known reserves, so-called other currency holdings rose to 2.9 percent from 2.2 percent.

"Our main takeaway -- central banks are unenthusiastic about any of the 'G3' at the valuations that prevailed in the third quarter, and their diversification into small currencies probably represented a significant part of the impetus these currencies experienced," Barclays currency strategist Steven Englander wrote in a note to clients.

Commodity-linked currencies such as the Canadian and Australian dollars and the Brazilian real all rose against the dollar, euro and yen, which comprise the G3. Russia's central bank also said this month it intended to add Canadian dollars to its roughly $444 billion of gold and foreign exchange reserves, though it said the overall share will likely remain below 2 percent.