Credit Suisse Group AG joined larger rival UBS Group AG in triggering margin calls on wealthy clients who use Russian assets as collateral, after their value slumped in the wake of extensive sanctions imposed on the country.

Switzerland’s second-largest bank is asking rich customers to post more collateral after cutting lending values on Russian securities, according to people familiar with the matter who requested anonymity to discuss internal information. Other banks with wealth management arms including Banque Pictet & Cie SA have also cut lending values, Bloomberg reported earlier.

The extent of the margin calls and whether all have been met wasn’t immediately clear. But the speed of the Russian invasion of Ukraine and the response by the U.S. and Europe has left wealthy individuals invested in Russian assets facing frozen funds and demands for more collateral.

Credit Suisse declined to comment.

Russian assets and the ruble have slumped as the country’s economy is being targeted by sanctions over its invasion of Ukraine. The measures are hampering Russia’s ability to use reserves to defend its currency, sending the ruble into free fall. Several of the country’s largest banks have been blocked from parts of the global financial system and rating companies have cut the country’s creditworthiness to junk.

Bloomberg reported last week that several Swiss banks had reduced the amount they were willing to lend against Russian assets, in some cases to zero. Securities of sanctioned banks Sberbank of Russia PJSC and VTB Bank PJSC are among those, people with knowledge of the matter have said.

In a margin call, banks ask investors to add cash or securities to a portfolio that typically also includes some borrowed funds or securities when the market value falls below a predetermined limit, often during a market rout or other event. The bank can forcibly liquidate clients holdings if they are unable or unwilling to deposit the funds. 

This article was provided by Bloomberg News.