Russia’s ruble lost more than one-tenth of its value Monday, collapsing to a record low and raising fears that the Kremlin won’t be able to stem the slide as the price for oil, its main export, continued to fall.

The drop—the largest in a single day since 1999—brings the slump to nearly half since the start of the year and more than one-fifth this month. As the ruble fell, Russia’s central bank said the economy could shrink by as much as 4.7% next year if oil averages $60 a barrel, not far below the current price of Brent crude, the global benchmark.

The currency’s dive and forecasts of heightened economic pain raise the stakes for President Vladimir Putin, who is locked in a confrontation with the West over his intervention in Ukraine.

The Kremlin’s options for stemming the slide are narrowing. Earlier this year, the central bank sold nearly $75 billion to prop up the ruble, but with little effect. It allowed the currency to float freely in November, and has spent some $6 billion since then.

The central bank has shied away from large-scale interest-rate increases, which have the potential to cripple the economy.