The Securities and Exchange Commission (SEC) is reportedly investigating the circumstances around Apple's announcement about Steve Jobs taking a leave of absence from the company.
Bloomberg reports claim that the SEC is reviewing the sequence of events around the announcement to make sure that investors were not misled.
Shares rose after Jobs acknowledged that he was suffering from a simple hormone imbalance, but fell when he announced his leave of absence shortly afterwards.
"The good news flipped by the bad news makes one wonder what Apple knew," said James Cox, a law professor at Duke University in Durham, North Carolina.
"It is not surprising for the SEC to come in and look afterwards, given the pressure and publicity regarding its handling of a lot of cases."
Cox was referring to criticism of the SEC's response to Bernard Madoff's alleged $50bn Ponzi scheme.
Companies are not required by law to report on the health of their management teams, and the SEC would have to prove that Apple sought to profit from the announcements to make a case stick.
"It would be difficult, and certainly a new area of the law," said Peter Henning, a former federal prosecutor and SEC lawyer.
"You would have to pin down exactly what they knew. And, with a health issue, unlike a merger or a decline in revenue, it is not subject to definitive answers."
Apple, Jobs and the SEC were all unwilling to comment on the report. Jobs said in a telephone interview with Bloomberg News on 16 January: "Why don't you guys leave me alone? Why is this important?"
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