It was a painful day to be a Russian billionaire.

The combined net worth of the country’s wealthiest people fell by US$16 billion Monday -- erasing all of their year-to-year gains -- following last week’s U.S.-imposed sanctions.

All but one of the 27 Russian tycoons listed on the Bloomberg Billionaires Index lost money, led by Siberian nickel miner Vladimir Potanin, whose fortune declined US$2.25 billion. Lukoil PJSC Chief Executive Officer Vagit Alekperov saw his wealth tumble US$1.37 billion, while Viktor Vekselberg of Renova Group lost US$1.28 billion.

Vekselberg is one of seven Russian tycoons sanctioned last week by the Trump administration in retaliation for Moscow meddling in the 2016 U.S. presidential election. He took steps Monday to limit the exposure of his Swiss holdings to the sanctions.

Oleg Deripaska, who was also among those sanctioned, lost US$905 million on Monday and has seen his fortune dwindle by more than US$2 billion over the past two trading days. His losses stemmed from his industrial conglomerate En+ Group Plc, whose shares have plunged 54 per cent since Thursday, according to London Stock Exchange data. Through EN+, Deripaska owns half of United Co. Rusal, the giant aluminum producer that was also slapped with sanctions.

The MOEX Russia Index of stocks climbed 1.4 per cent by 1:21 p.m., after falling 8.3 per cent Monday, the most in four years. The ruble weakened 3.2 per cent to 62.67 versus the dollar, extending its slump this week to 7.2 per cent.