The new report covers the foreign reserves of 138 IMF members, who hold 55 percent of the $9.26 trillion in reserves held across the world. China, by far the largest holder of US Treasury bonds, refuses to report the currencies held in its $2.85 trillion of reserves. But, in evidence of the dollar's slight decline in importance over the period, "other currencies" in the report jumped to a 4.4 percent share of total reserves, up from 4.0 percent on September 30. The euro's share slipped to 26.3 percent from 26.9 percent, while the pound and the Swiss franc remained stable, at 4.0 percent and 0.1 percent, respectively. The yen rose to 3.8 percent from 3.6 percent. The fourth quarter data "supports the notion that central banks are sticking to relatively stable allocations of major currencies (the dollar and euro) rather than pursuing aggressive diversification strategies," Nomura Global FX Research analysts said in a client note.

"Furthermore, the data suggest renewed demand for 'other' currencies and the yen," they added. The IMF publishes the figures in dollars. Any depreciation against the dollar automatically reduces the US currency's share in reserves, and inversely any appreciation increases it. The IMF noted that by the end of the fourth quarter, the euro had lost 2.0 percent of its value against the dollar, while the yen gained 2.4 percent.