At the same time, Mr. Putin will be under pressure to repay the loyalty of his associates, who might reasonably want assurances that they will not face prosecution or exile, as has happened in the past to a half-dozen or so members of the first generation of so-called oligarchs in post-Soviet Russia. “The future for them without Putin is quite a bit more questionable and less promising,” said Mikhail Dmitriev, an economist at the Center for Strategic Research in Moscow.

On paper, Mr. Putin shows no connection to big riches. In a disclosure required by the electoral authorities, he declared an average annual income of about $153,000 over the last four years from a salary, military pension, investments and bank interest. His wife earned about $1,200 a year on bank deposits. He also declared owning a third of an acre of land near Moscow, an 800-square-foot apartment and a garage in St. Petersburg, as well as three vehicles — two 1960s antiques and a 2009 Lada — and a tow-hitch trailer. Mr. Putin and his wife declared slightly less than $500,000 in bank savings.

That contrasts starkly with at least a dozen acquaintances of Mr. Putin, many dating to his early career and social life in St. Petersburg, whose wealth until recently was largely in the shadows. But much is now public, owing to disclosure rules on Western stock exchanges, due diligence by foreign companies, lawsuits and a newfound aggressiveness in the Russian opposition news media.

Rosneft now sells a significant portion of its oil through Mr. Timchenko’s privately held, Netherlands-based trading company, called Gunvor. The company acknowledges controlling about a fifth of Russia’s crude oil exports, meaning the proceeds from roughly 5 percent of Russia’s total economic output are channeled through Mr. Timchenko’s trading operation.

Shares in Rosneft itself are scheduled to be sold later this year as part of the new privatization wave.

In cables released by the antisecrecy group WikiLeaks, American diplomats described Gunvor as of “special note” in a broader system of opaque dealings during the oil boom. The company, a 2009 cable said, is “rumored to be one of Putin’s sources of undisclosed wealth.”