Berkshire Hathaway Inc's
The news from the 81-year-old Oracle of Omaha is likely to intensify the already brewing debate about the succession plan at Berkshire Hathaway, a conglomerate that employs more than 270,000 people in more than 70 businesses around the world.
Buffett told investors in late February that Berkshire had identified his successor, but in typically circumspect fashion, declined to say who it was - and ultimately admitted that even the chosen one does not know, himself.
Buffett said in a statement he will begin a two-month treatment consisting of daily radiation treatments starting in mid-July. This will limit his ability to travel during that time, he added.
Berkshire shares fell 1.5 percent in after-hours trading on the news. The widely held Class B shares are up 5.9 percent year-to-date, half the gains of the broader S&P 500.
One Berkshire investor said it was reasonable to assume people would panic at the news of Buffett's illness, but that nothing had actually changed in the case for the stock.
Despite the news, this is not a reason to sell (Berkshire). Fundamentals are still good at the company and the clear succession plan does give clarity about the future path of the firm, said Michael Yoshikami, chief executive of Destination Wealth Management in California.
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 centre 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.
(Reporting By Phil Wahba and Ben Berkowitz; Editing by Gary Hill)