(Reuters) - Top executives at U.S. pharmaceutical company Novavax Inc aren’t waiting to see how well their COVID-19 vaccine works before they reap the financial rewards. Chief Executive Stanley Erck and three of his top lieutenants have sold roughly $46 million of company stock since the start of last year, according to a Reuters review of securities filings, capitalizing on a near 3,000% rally in Novavax shares fueled by investors betting on the success of the shot under development. Erck cashed out $8.7 million over the course of 2020, eclipsing the $2.2 million in shares he sold in the previous five years. The stock sale amounts to more than 20% of his vested stake in Novavax, or less than 10% if stock options that are yet to vest are counted, according to the review of the filings, an analysis by compensation consultant Farient Advisors LLC and a company spokeswoman. The lucrative liquidations, which have not previously been reported, underscore the transformation in Novavax’s fortunes during the global pandemic and the opportunity for its executives to lock in big profits from market optimism. There is no certainty that Novavax, which has yet to bring a vaccine to market, will be successful in its latest endeavor. The 34-year-old company has become a key contender in a global race to develop vaccines against COVID-19 thanks to $1.6 billion in taxpayer funding it received under the U.S. government’s “Operation Warp Speed” program. The Gaithersburg, Maryland-based company was worth only $250 million until about a year ago, when news of its experimental vaccine and its participation in Operation Warp Speed drove its valuation up to as much as $11 billion. A Novavax spokeswoman said the executives were responsible for the stock sales. “Our leaders remain confident in the value and potential of our vaccines and are passionately committed to contributing to ending the COVID-19 pandemic and improving public health around the world,” Novavax said in a statement. “They continue to hold substantial personal and professional interest in Novavax’ success as well as a financial one.” The executives did not respond to requests for comment. The Novavax spokeswoman did not make the executives available for interview. (GRAPHIC: Novavax stock chart - ) Only peers at rival biotech company Moderna Inc have sold more stock than Novavax executives among major firms that received U.S. taxpayer funding to develop or manufacture COVID-19 vaccines, according to an analysis by consumer advocacy group Accountable.US which looked at transactions from May to November 2020. Moderna’s COVID-19 vaccine is already being rolled out after it was approved by the U.S. Food and Drug Administration on Dec. 18. To be sure, many of the other companies in the vaccine race are far larger than Moderna and Novavax, limiting the impact of news on their shares. Pfizer Inc’s vaccine was the first to be approved by the United States on Dec. 11. AstraZeneca Plc won approval in Britain for its vaccine on Dec. 30, and Johnson & Johnson is scheduled to report trial data in January, lining it up for U.S. authorization in February. Novavax, meanwhile, announced last month that it had begun a late-stage trial of its COVID-19 vaccine in the United States, after delaying it twice due to issues in scaling up its manufacturing. It expects to see the results from another late-stage trial, in the United Kingdom, sometime in the first quarter of 2021. Slideshow ( 2 images ) Early-stage data from Novavax’s small clinical trial of its vaccine have shown it produced high levels of virus-fighting antibodies and the company has already inked supply deals for it with countries including Japan, Canada, Australia and the UK as well as with the United States. Some corporate governance experts said Novavax offered a striking example of how boards use company stock to incentivize their management teams without always linking them closely to their long-term prospects. “Board members should have insisted that the executives held onto their shares,” said Sanjai Bhagat, a finance professor at the University of Colorado. “Then they would have the incentive to do everything that they could to get the vaccine out sooner.” The chairman of Novavax’s board, James Young, did not respond to requests for comment. Jesse Fried, a Harvard Law School professor and a member of the research advisory council at proxy advisor Glass, Lewis & Co., said he didn’t think it was inappropriate to reward executives during the drug development process. “It may be a once in a lifetime opportunity to lock in huge gains,” said Fried. “I don’t have a problem with them making a lot of money even though they don’t have a drug yet.” Investors will get to express their views on the stock sales this summer at Novavax’s annual shareholder meeting, where they will be asked to approve the company’s board of directors and executive compensation. “If investors think the actions were unreasonable, they will ask what the board’s role was in overseeing this disposition of stock,” said Peter Kimball, head of advisory and client services at ISS Corporate Solutions, which advises companies on corporate governance. To be sure, last year Novavax awarded more than $85 million worth of stock options to executives, including $41.1 million to Erck, that are specifically tied to the vaccine’s development and cannot be exercised until they start vesting in August. However, this award was contingent on the vaccine entering a mid-stage clinical trial, not its eventual success, Reuters reported in July. Development milestones for drugs can trigger big share price moves so pharmaceutical executives sometimes adopt a fixed schedule for stock sales -- known as a 10b5-1 plan -- to avoid any suggestion of insider trading. Novavax executives disclosed in regulatory filings that they sold some of their shares using such trading plans. A Novavax spokeswoman said executives adopted the plans in the summer, but did not provide the exact dates. Moderna and Pfizer disclosed the dates when trading plans were adopted by executives in their filings. Such disclosure is not required and is less common across U.S. companies, said Dan Taylor, a professor at the Wharton School at the University of Pennsylvania. Out of the approximately $46 million of stock sold, Novavax chief commercial officer John Trizzino sold about $13 million, while Novavax’s head of research and development, Greg Glenn, sold about $13.4 million, according to securities filings. The company’s chief legal officer, John Herrmann, sold $10.9 million. Executives at Emergent BioSolutions Inc, Pfizer and Johnson & Johnson, also recipients of federal funds, sold $24 million, $10 million and $4 million worth of stock, respectively, according to Accountable.US. Moderna executives sold $166 million worth, according to Accountable.US. Nina DeLorenzo, a spokeswoman for Emergent BioSolutions, said in a statement that the majority of the transactions were planned in advance under a 10b5-1 trading plan adopted in February by the company’s executive chairman Fuad El-Hibri. “Our executive team and board of directors are held to the highest ethical standards and follow strict compliance with company policies for equity holding, as well as all laws and regulations governing financial transactions,” according to the statement. Pfizer and Moderna did not respond to requests for comment.