Dec. 4 (Bloomberg) -- Russia is wasting its cash reserves by propping up the ruble as lower oil prices drive away investors from commodity-led economies, according to Brown Brothers Harriman & Co.

“The pressure on the ruble will remain and Russia shouldn’t try to resist it by depleting its reserves,” said Win Thin, a currency strategist at Brown Brothers Harriman in New York. “Oil producers are really struggling in terms of trade shock.”

The CHART OF THE DAY shows that the 16 percent slide in the ruble is yet to match the decline in the currencies of commodity exporters including Australia and Mexico, which have fallen 33 percent and 24 percent versus the dollar since July.

Urals crude, Russia’s main export blend of oil, has slumped 68 percent since July to $43 a barrel, below the $70 average needed to balance the country’s budget next year. Russia has spent $148 billion or a quarter of its international reserves since August to defend the ruble.

Of the other “commodity currencies”, the Brazilian real slid 33 percent against the dollar, the New Zealand dollar dropped 30 percent, the Chilean peso 21 percent and the South African rand fell 23 percent.

The Reuters/Jefferies CRB Index of 19 raw materials has dropped 45 percent in the past six months.

To contact the reporter on this story: Laura Cochrane in London at lcochrane3@bloomberg.net

Last Updated: December 3, 2008 19:22 EST