This story has been updated to clarify that Jim Cramer’s email was read on the air before being tweeted by CNBC shortly afterward and that CNBC did not answer MarketWatch’s questions on the exact timeline of events.

Apple Inc. CEO Tim Cook’s decision to give a rare midquarter update on the company’s performance in a private email to CNBC’s Jim Cramer on Monday may have violated federal disclosure rules, lawyers said Monday.

In the email, confirmed by Apple AAPL, +3.03% to MarketWatch, Cook said that iPhone activations have accelerated over the past few weeks, despite growing economic concerns in China and the government’s moves to devalue the yuan. He also wrote that Apple’s App Store had recorded its best performance of the year in China during that time.

“ ’The SEC will undoubtedly want to take a look at this.’ ” — Thomas Gorman, Dorsey & Whitney

“Obviously I can’t predict the future, but our performance so far this quarter is reassuring,” Cook wrote.

However, the private disclosure, which was tweeted by CNBC reporter Carl Quintanilla and read on air at CNBC, may have violated the Securities and Exchange Commission’s fair-disclosure regulation, white-collar lawyers told MarketWatch. The rule, deemed murky and often contested by companies, addresses how publicly traded companies disclose material nonpublic information to certain individuals or entities.

“The SEC will undoubtedly want to take a look at this,” said Thomas Gorman, a partner at the law firm Dorsey & Whitney who defends companies and individuals facing SEC and other regulatory investigations. At the very least, the SEC will contact Apple to seek context for the disclosure, he said.

While the media typically get a pass under the disclosure rules, Cramer also co-manages a portfolio, Action Alerts PLUS, that has a long position in Apple, according to a recent disclosure on the website TheStreet.

CNBC did not respond to questions about the exact timing of when Cramer received the email and when it was first read aloud on air.

Bill Singer, another lawyer and owner of the BrokeAndBroker.com industry blog, said the SEC has long grappled with regulation in the age of social media and will likely investigate Cook’s email to determine whether the CEO overstepped his bounds with the private exchange.

“I certainly could see, in some circumstances, where the SEC would want to review the conduct and think it is a violation of Reg FD,” Singer said. “It constitutes a disclosure giving certain individuals the benefit before it was percolated by the rest of the public, during a fast-moving, extraordinary market.”

The SEC declined to comment on the Cook email and any investigation it may undertake. Apple declined to comment beyond confirming the email.

In 2013, the SEC ruled that companies could make public disclosures on social-media platforms such as Facebook Inc. FB, -1.73% and Twitter Inc. TWTR, -0.62% after Netflix NFLX, +3.70% CEO Reed Hastings disclosed record streaming user growth via a Facebook post that sent the company’s stock skyrocketing.