Shares were down 1.16% to $56.93 in mid-day trading following Dimon’s announcement after the bell yesterday about his illness. They had dipped as low as $56.83 early on.

Dimon’s cancer is considered curable, he said in a note to employees and investors, and he will continue to be active at JPMorgan (JPM) while undergoing treatment. According to the note Dimon sent out, he’ll be undergoing an eight week course of chemotherapy and radiation. He also noted that doctors say the cancer has not spread to anywhere else in his body.

Despite the positive outlook, the announcement has created uncertainly around the company and raised questions about its succession plans. The head of the corporate and investment bank Daniel Pinto, chief operating officer Matt Zames, consumer banking head Gordon Smith and asset management chief Mary Erdoes all may be able to step into the CEO position in the short or long-term, Reuters noted.

Dimon, the longest-serving CEO of the major Wall Street banks, has been CEO of JPMorgan since 2005 and added the chairman’s role in 2006.