(Adds comments from corporate governance expert, details on other companies with ailing CEOs)
Oct 18 (Reuters) - United Continental Holdings Inc remained silent on the medical condition of its new chief executive officer, who was admitted to the hospital Thursday, prompting questions from observers about who will lead the company in his absence.
The airline said Friday that Oscar Munoz had been admitted to a hospital without providing further details. A source familiar with situation told Reuters the 56-year-old had suffered a heart attack.
However, as of Sunday night, United had declined to provide any updates about Munoz' health or state who will handle his responsibilities.
"We need to know who is speaking on the behalf of the company and who is accountable for the decisions of this great airline," said Jeffrey Sonnenfeld, a corporate governance expert and a professor at the Yale School of Management.
While United might be waiting to provide comment out of respect for Munoz' privacy, the company also has an obligation to shareholders, Sonnenfeld said.
"Munoz is entitled to his privacy if he doesn't want to be CEO," he said.
Munoz' health problems come barely a month after Munoz took on the job of improving the profitability and reputation of United, the No. 2 U.S. carrier by capacity.
Munoz and his family could not be reached for comment. It is not known where Munoz is being treated.
United's shares closed down 3.1 percent after the news, at a one-week low of $55.97. They have dropped nearly 17 percent this year.
United acknowledged in a short statement on Friday that Munoz's family informed the company he had been hospitalized the day before, and said it would provide "further details as appropriate."
United has an obligation to disclose material developments, wrote John Coffee, a professor specializing in corporate governance issues at Columbia University's law school, in an email. "It is the obligation of the company to keep the market informed of material developments and this seems clearly material to me," Coffee wrote.
It is puzzling why the company has not stated who will take over for Munoz in the meantime, said Greg Taxin, chief investment officer of New York-based Luma Asset Management, and founder of corporate governance research firm Glass, Lewis & Co.
"It's probably silly or foolish that they just haven't satisfied people's desire to know how the chain of command is working," Taxin said. "On the other hand, I presume the CEO of United Airlines goes on vacation on a regular basis, and he's not around to answer question or make decision and things run just fine.