Warren Buffett on Wednesday appointed Gregory Abel and Ajit Jain to the Berkshire Hathaway board as vice chairs, hinting that one of them is the most likely heir to the Oracle of Omaha at the helm of his sprawling, market-beating conglomerate. Buffett told CNBC this is "part of a movement to succession over time." Abel, 55, will be vice chair of noninsurance businesses and will likely be seen by Wall Street as the most likely to ascend into Buffett's role eventually. Abel currently is the chairman and CEO of Berkshire Hathaway Energy Company, which he joined in 1992. Jain, 66, was named vice chair of the insurance operations. Jain is the executive vice president of National Indemnity Company and joined the Berkshire Hathaway Insurance Group in 1986. The company's Board of Directors also voted to increase the number of directors to 14 from 12.

Greg Abel, chairman and chief executive officer of Berkshire Hathaway Energy Co., center, speaks with attendees before the start of the Berkshire Hathaway Inc. annual meeting in Omaha, Nebraska, U.S., on Saturday, May 6, 2017. Daniel Acker | Bloomberg | Getty Images

But Berkshire Hathaway also said Buffett, 87, and 94-year-old partner Charlie Munger will continue in their respective roles as chairman/CEO and vice chairman and be in charge of significant investment decisions for the company. After the announcement, Berkshire's B share class were slightly in trading. Buffett also said on CNBC's "Squawk Box" the appointment announcement is not related to any issues from his health. Speculation about who will succeed Buffett as head of the unique conglomerate has picked up in recent years given his advanced age. Buffett discussed his succession plan in his annual letter from 2014, saying that he and Munger had already identified who should succeed him. "Our directors believe that our future CEOs should come from internal candidates whom the Berkshire board has grown to know well. Our directors also believe that an incoming CEO should be relatively young, so that he or she can have a long run in the job. Berkshire will operate best if its CEOs average well over ten years at the helm. (It's hard to teach a new dog old tricks.) And they are not likely to retire at 65 either (or have you noticed?). In both Berkshire's business acquisitions and large, tailored investment moves, it is important that our counterparties be both familiar with and feel comfortable with Berkshire's CEO. Developing confidence of that sort and cementing relationships takes time. The payoff, though, can be huge. Both the board and I believe we now have the right person to succeed me as CEO – a successor ready to assume the job the day after I die or step down. In certain important respects, this person will do a better job than I am doing." For many years, it was thought that person was Jain because Buffett has often spoken about him so highly.

Ajit Jain, head of the Berkshire Hathaway reinsurance business. Daniel Acker | Bloomberg | Getty Images