It's back again -- ruble vertigo. The Russian currency is losing value faster than anybody could have feared, in one day making nearly the entire leap from 3,000 to 4,000 per dollar, after taking three months to span the previous thousand and more than a year for the thousand before that.


What is going on? Economists say that the Central Bank has spent too much money propping up the ruble throughout the year, leaving the currency overvalued against its foreign counterparts and making a major devaluation inevitable. But in an economy where statistics are about as accurate as crystal balls, nobody is willing to say exactly how overvalued the currency was, or how much further it is likely to fall.


Acting Finance Minister Sergei Dubinin and a pantheon of Central Bank officials have vaguely said that the ruble's fall no longer has anything to do with underlying economic factors, blaming it on "speculation," as if that would satisfy Russians desperate to know how little their salaries are going to be worth by the end of the month.


But as the ruble continues to plummet, only one thing is clear: the Central Bank has deliberately stepped back from the market, cutting off the intervention that had coaxed the currency into a steady slide for most of the year.


The Central Bank's policy on the market has two possible explanations:


1) The bank has lost control: It's hard-currency reserves, estimated at $5 billion at the end of September, are simply not large enough to support the currency any more, meaning that the bank can do nothing but sit on the sidelines and watch.


2) The bank wants the ruble to fall. A cheaper ruble not only makes Russian products more competitive on domestic and foreign markets, but helps the government close the budget deficit by increasing tax revenues and decreasing the cost of paying ruble debts with hard currency.


Both possibilities -- and the two are not mutually exclusive -- point to irresponsibly short-term thinking. In the first, the bank simply violated its own stated policy by interfering with the ruble's equilibrium, which led to a disproportionate demand for dollars and made a crash unavoidable.


The second scenario, which has gained the support of most traders, suggests the Central Bank sacrificed confidence in the Ruble, placing exports and accounting tricks above investment and the health of the country's ruble-based capital markets.


In either case, the damage has been done: Commercial banks have been reminded how profitable the dollar can be, while businesses and financial markets have suffered a setback that only several months of stability can correct. Hopefully, the Central Bank will stop the rot soon.