Inovio Pharmaceuticals (NASDAQ:INO) has been one of the most volatile biotech stocks on the market as the company works on developing a potential COVID-19 coronavirus vaccine. After the markets closed on Thursday, Inovio released its fourth-quarter and 2019 full-year financial results.

As can be expected for an early-stage biotech stock, revenues were minimal overall, with the company reporting significant net losses. Total revenue came in at just $279,000 for the quarter, a significant decrease from the $2.5 million reported in Q4 2018. Inovio's net loss for the quarter came in at $37.7 million, which has slightly worsened from last year's $33 million net loss.

A vial labeled COVID-19 with a pipette in a laboratory.

Image source: Getty Images.

Inovio has a number of early-stage candidates undergoing development. Most notable is INO-4800, its promising COVID-19 treatment.

The biotech company had received a $9 million grant from the Coalition for Epidemic Preparedness Innovations (CEPI) earlier this year to develop a vaccine to counter the virus. Inovio also received a $5 million grant from the Bill and Melinda Gates Foundation to further test and scale a potential device that would allow the convenient delivery of the INO-4800 vaccine.

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Shares of Inovio tumbled around 28% in after-hours trading on Thursday following the news. Although most Wall Street analysts covering the stock are bullish on the company's prospects, others have been more skeptical.

Notable short-seller Citron Research stated earlier this week that the U.S. Securities and Exchange Commission (SEC) should shut down Inovio and investigate claims made by the company. Inovio's stock fell by around 50% following the statement and has struggled to recover ever since.