Jamie Dimon, the chief executive and chairman of JP Morgan Chase, has been diagnosed with a curable form of throat cancer.
Dimon, 58, will now undergo an eight-week course of radiation and chemotherapy treatments.
He indicated in a note to shareholders and staff that the cancer had been caught early and was considered curable by doctors, whom he said had given him an "excellent" prognosis.
During the treatment period Dimon said that business would be run "as normal" and that he would continue to be "actively involved" in the business.
Shares in JP Morgan remained relatively unaffected in after-market trading.
Dimon has canceled a scheduled trip to Europe to meet with the Italian and Greek prime ministers. He was also scheduled to visit the UK, Spain and Germany.