To be fair, as fellow Fool Dan Caplinger pointed out at the time, the sanctions didn't target Yandex specifically, but rather focused on roughly two dozen Russian government officials and oligarchs. But Yandex plunged 12% on April 9, 2018, anyway as investors in Russian companies reacted to the news.
Yandex continued to fall later in the month even after the company posted impressive first-quarter 2018 results, including nearly 29% year-over-year revenue growth and a steady majority share (56.5%) of the Russian internet search market. Yandex's supplementary investments in services like Yandex.Taxi, its classifieds business, and media services also contributed to accelerating revenue growth.
If it's any consolation, Yandex is up more than 33% over the past year as of this writing -- the result of the company's undeniable strength in its core internet search market and the success of its smaller bets. But given the current geopolitical environment, it's hardly surprising to see the stock still trading well off its 52-week highs.