Andre Esteves, the Brazilian billionaire who transformed Grupo BTG Pactual into the largest independent investment bank in Latin America, was arrested in the corruption probe that has shaken the country’s political and economic leadership. BTG’s shares tumbled the most ever.

Federal police arrested the financier in Rio de Janeiro after first searching for him in Sao Paulo, a police press official said by telephone Wednesday, declining to provide details on why the arrest was made. Esteves is under temporary arrest for a maximum of five days, according to an official for the federal Supreme Court, which authorized the action. Police also detained the government’s leader in the Senate, Delcidio Amaral, on suspicion of harming the investigation, said the official who asked not to be identified because he’s not authorized to comment publicly.

Esteves and Amaral are among the highest-profile arrests since the investigation into a pay-to-play scheme between an alleged cartel of builders and state-run oil producer Petroleo Brasileiro SA began in March 2014. The probe has helped tip Brazil into a recession and left Brazilian President Dilma Rousseff fighting for her political survival.

The move “takes the Petrobras probe to a whole new level and shows the depth and breadth of a scandal that’s engulfing Brazil’s political and corporate establishment,” said Nicholas Spiro, managing director at Spiro Sovereign Strategy, in London. “The scandal is becoming more debilitating by the day.”

Brazil police intercepted a conversation in which Amaral asks someone close to former Petrobras director Nestor Cervero that Cervero not mention him nor Esteves in testimonies, O Estado de S. Paulo reported, without saying how it got the information.

“We’re surprised with the arrest, it must be a big mistake,” said Eduardo Marzagao, a spokesman for Amaral, who added that Amaral’s lawyer is traveling to Brasilia. “Certainly this will be showed to have been a great error.”

BTG Pactual said in an e-mailed statement that it is cooperating with the investigation and is willing to explain whatever is necessary to authorities, without providing further details. The bank’s stock plunged as much as 19 percent in early Sao Paulo trading.

More than 100 people have already been arrested, including former top executives at Petrobras and Brazil’s biggest construction conglomerate. The sweeping investigation into Petrobras — dubbed “Carwash” by prosecutors after a gas station used to launder money — has helped make Brazil’s real the world’s worst-performing major currency this year. Brazil’s economy is forecast to shrink more than 3 percent this year, according to a central bank survey of economists.

Esteves, chairman and chief executive officer of BTG Pactual, has one of Latin America’s largest fortunes, worth $2.7 billion, derived mostly from his stake in the investment bank.

Esteves in 2006 sold what was then Banco Pactual to UBS Group AG for $2.6 billion. He moved to London to be global head of fixed-income sales and trading for UBS the following year and offered to buy a controlling stake in the Swiss bank during the 2008 financial crisis. UBS rejected the bid and Esteves quit to form BTG, which he has joked stands for Back to the Game or Better than Goldman. In 2009, UBS agreed to sell to him and some of his former partners Pactual for $2.5 billion.

BTG teamed up with Petrobras and other partners in 2010 to create Sete Brasil, a rig-supplier whose former operating chief admitted in plea bargains to crimes of corruption