Berkshire HathawayCEO announced Tuesday that he has been diagnosed with stage I prostate cancer.
"The good news is that I've been told by my doctors that my condition is not remotely life-threatening or even debilitating in any meaningful way," he said in a letter to shareholders. "I received my diagnosis last Wednesday. I then had a CAT scan and a bone scan on Thursday, followed by an MRI today. These tests showed no incidence of cancer elsewhere in my body." (Click here to read the full letter.)
The company's class B shares fell 1 percent in after-hours trading after rising 1.4 percent in regular trading. Class A shares rose 1.5 percent in regular trading on Tuesday.
Buffett said he will begin a two-month treatment of daily radiation in mid-July. During this time, he will restrict his travel but does not plan to change his daily routine otherwise.
"I feel great — as if I were in my normal excellent health — and my energy level is 100 percent," he said.
The news from the 81-year-old "Oracle of Omaha" is likely to intensify the already brewing debate about the succession plan at Berkshire.
Buffett told investors in late February that Berkshire had identified his successor, but declined to say who it was — and ultimately admitted that even the chosen one does not know, himself.
Following the announcement, Buffett told CNBC's Becky Quick that there will be no changes to the succession plan and that his potential successor has still not been notified.
"Despite the news, this is not a reason to sell Berkshire," said Michael Yoshikami, CEO of Destination Wealth Management. "Fundamentals are still good at the company, and the clear succession plan does give clarity about the future path of the firm."
Berkshire is less than three weeks away from its annual meeting, which draws more than 40,000 shareholders to its headquarters in Omaha, Nebraska, where in a festival-like atmosphere Buffett holds center stage.
This year's meeting was expected to focus to some degree on succession, as well as the investment case for Berkshire. For the first time ever, Buffett is expected to take questions from sell-side analysts at the meeting.