Shares in Russia's Mail.ru have surged more than 30% on their London debut, after the internet group raised $912m (£563m) in a stock market flotation.
Strong demand helped the group, an owner of a 2.38% stake in Facebook, price its shares at $27.7 each, the top of the firm's range.
The shares are now being traded conditionally, ahead of the formal start of trade on 11 November.
The initial public offering (IPO) values Mail.ru at $5.71bn.
Mail.ru is one of the few chances for investors to hold some indirect stake Facebook, the world's largest and still rapidly growing social networking site.
The London listing makes Mail.ru Europe's largest listed internet business.
"Mail.ru has certainly hit a sweet spot," said Chris Weafer, a Uralsib analyst.
During the past few years the company, formerly known as DST, invested about $1bn in many Russian and foreign internet companies.
It controls the huge Russian freemail service Mail.ru, Russian social network Odnoklassniki and instant messenger ICQ.
Among other investments, it has stakes in Zynga, the maker of the FarmVille and FrontierVille games; deals website Groupon; Russian social network VKontakte and payment processing company Qiwi.