(Bloomberg) -- The Swiss National Bank’s foreign-currency reserves rose to a record in December after an appreciation of the franc forced the institution to end a two-year hiatus in interventions.

Holdings increased to 495.1 billion francs ($490 billion) from a revised 462.7 billion francs in November, the central bank based in Zurich and Bern said on its website today. The holdings are calculated according to International Monetary Fund standards at the beginning of every month.

The SNB said on Dec. 18 that it had resumed purchases of foreign currencies after the franc hit its strongest since 2012 amid a weakening of the Russian economy and the prospect of more euro-area stimulus by the European Central Bank. It imposed a negative deposit rate to stave off capital inflows and lowered its target range for three-month franc Libor to reinforce its three-year-old minimum exchange rate of 1.20 per euro.

Negative rates don’t hinder the SNB in its ability to wage unlimited currency interventions, President Thomas Jordan told Swiss television SRF earlier this week.

As of the end of the third quarter, the SNB held 45 percent of its reserves in euros and 29 percent in dollars. The bulk was invested in highly rated government bonds, with 16 percent in equities.

--With assistance from Joel Rinneby in Stockholm.

To contact the reporter on this story: Catherine Bosley in Zurich at To contact the editors responsible for this story: Fergal O’Brien at Jana Randow, Zoe Schneeweiss