As for Bank Rossiya, he went on: “As far as I recall, this is a medium-sized bank. Personally, I did not have an account there, but I will definitely open one on Monday.” He later directed the presidential administration to begin depositing his official salary — roughly $7,500 a month — into a Bank Rossiya account.

Mr. Kovalchuk later gave a rare television interview with Dmitry K. Kiselyov, a prominent news anchor and ardent defender of Mr. Putin’s Russia. The president’s public gesture, Mr. Kovalchuk said, had prompted a flood of new customers, including an old, impoverished woman who wanted to deposit her life savings. For a bank with billions in assets, “this old woman means nothing financially, but the fact is that is worth more than any financial investments,” he said. “There is a Putin factor, and it is unconditional. The fact is that people intuitively feel which side of the barricades business stands on.”

Mr. Putin’s efforts to protect the bank were not just symbolic. He ordered the Central Bank to provide assistance if needed. State-owned energy companies transferred accounts to Bank Rossiya, and the governors of St. Petersburg and the surrounding Leningrad region told state institutions in their jurisdictions to do the same, according to Russian news reports. Additionally, in the lower house of Parliament, the main party loyal to Mr. Putin provided the margin needed to rescind the law effectively limiting Video International to just 35 percent of the advertising-placement market.

And on April 10, the Market Council stepped in. The council, which regulates Russia’s $35 billion wholesale electricity market, is a nonprofit organization with 22 members representing government ministries as well as major producers and suppliers of electricity. One of the council’s members is an executive at Inter RAO UES, a private enterprise spun off from the former state electricity monopoly. Its chief executive is Mr. Kovalchuk’s son, Boris; its board chairman is Mr. Sechin, the president of the state-owned oil giant Rosneft and one of Mr. Putin’s closest advisers.

The council met at its office in Moscow’s World Trade Center. A spokeswoman declined to discuss the vote, except to say that a quorum attended, explaining that she did not want to contribute to an “anti-Russian” article. The decision to shift the business to Bank Rossiya, she said, was one of several routine actions taken during a regular meeting that day. In remarks published on the council’s website in May, its director, Maksim S. Bystrov, said Bank Rossiya had “brought us” a proposal with lower commissions than those charged by the previous bank, Alfa. But he declined to provide details, and Alfa Bank declined to comment.

As the United States and Europe continue to ratchet up the economic pressure, it is an open question how long the government can continue to prop up the growing number of institutions faced with sanctions. Russia’s economy had been struggling even before the annexation of Crimea. The European Bank for Reconstruction and Development recently predicted that, with the added impact of Western sanctions and Mr. Putin’s retaliatory embargo on Western goods, the economy could contract next year.

Other companies are lining up behind Bank Rossiya, hoping for bailouts. The government recently announced that it would pump $6.6 billion into two state-controlled banks whose access to foreign capital has been cut. And Mr. Sechin’s Rosneft has requested a $42 billion loan.

For his part, Mr. Putin has denounced the sanctions as unfairly targeting people with no influence over Russia’s policies on Crimea or Ukraine. “Yes, these people are my friends and I’m proud to have such friends,” he said at an economic forum in St. Petersburg in May. “They are true patriots and their business is oriented towards Russia. Have these sanctions done damage to them? Yes, they have. If I’m being honest, they have. But they are seasoned entrepreneurs and brought all their money back to Russia, so don’t worry about them too much.”