The arrest of one of Brazil's richest men has sent shares in his bank tumbling.

Andre Esteves was completing his first day in jail on Thursday after being accused of obstructing a probe into corruption at the state oil company, Petrobras.

Esteves denies all the accusations.

Shares in his BTG Pactual bank dipped 21 percent Wednesday on the Sao Paulo stock market. And on Thursday, rating agency Moody's said it was placing the bank's ratings on review for downgrade, which triggered another session of losses for BTG.

Analyst Silvio Campos Neto says the impact of the investigations could be felt in every business related to BTG Pactual.