The sale of Intel Corp. stock by Chief Executive Brian Krzanich while the company was handling concerns about security flaws in its chips was a highly unusual move that risked attracting regulatory scrutiny, according to lawyers and analysts who follow executive stock sales.

The trade took place on Nov. 29, nearly six months after Intel was informed about the vulnerabilities , which could enable hackers to access user data in chips made by Intel and others. Mr. Krzanich sold shares and exercised stock options valued at a total of $39 million, netting him nearly $25 million, according to regulatory filings made at the time.

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“At first glance, it’s a very unusual type of thing that shareholders and directors would want a fairly tight explanation about,” said David Larcker, a professor of securities law at Stanford University. “It may be fine, but it’s the kind of thing you’d want to really understand and be transparent with shareholders about.”