New York (CNN Business) Moderna set off a frenzy on Wall Street earlier this month when it announced positive, preliminary results from its coronavirus vaccine trial. As the hype grew, the young biotech company and its leading investor wasted no time capitalizing on the briefly surging stock price.

Even as critics accused Moderna of overhyping the results released on May 18, a series of transactions were executed before its share price fizzled over the next week. The timing of those deals, former SEC officials said, appear to be "highly problematic" and should be investigated for potential illegal market manipulation.

Just hours after revealing the promising vaccine results, Moderna (MRNA) sold 17.6 million shares to the public. That share sale, unveiled after the closing bell on May 18, was priced at $76; Moderna traded at just $48 as recently as May 6. The deal instantly raised $1.3 billion.

Two of Moderna's top executives also cashed in on the boom at their company, which had suddenly amassed a $29 billion market value despite the fact it has no marketed products. ... Moderna's chief financial officer and chief medical officer sold nearly $30 million of shares combined on May 18 and May 19. ... Days later, Moderna's leading shareholder, venture capital firm Flagship Pioneering, sold 1 million shares on May 21 and 22 at an average price of $69.47, according to filings reviewed by CNN Business. The sales raked in $69.5 million for the venture capital firm. ... Moderna closed at $55.54 on Thursday, down 36% from its peak on May 18 when the vaccine results were announced.