(Bloomberg) -- Novavax Inc. shares fell the most in almost four years on Thursday after the company announced it had cut its vaccine supply to the UK and was seeking additional equity and debt.

The biotech company, which makes vaccines to fight against infectious diseases, said it was offering $125 million in shares and $125 million in convertible bonds via JPMorgan Chase & Co., Jefferies Financial Group Inc. and Cowen Inc. It also said in company filings that it was obliged to repay the UK government after its agreement to supply Covid-19 vaccines was halved.

Novavax shares fell more than 34% after the announcements, closing at $11.32, its lowest since March 2020. It is the largest single-day loss for the company since February 2019, when it lost 67% after its vaccine trial for respiratory syncytial virus had disappointing results. Shares of Novavax have fallen 92% since the start of this year.

The capital raise and supply agreement changes are the latest in a recent string of obstacles for the company. Its Covid-19 vaccine — a majority of the company’s business — saw continued delays and was first approved for emergency use in the US in July of this year. More than 85% of Novavax’s revenue for the third quarter came from its Nuvaxovid vaccine for Covid-19, executives said during the company’s most recent earnings call, with most of the remaining 15% from grant revenue.

In total, Novavax has delivered 984,600 doses of its Covid vaccine in the US, a small fraction of the hundreds of millions by Pfizer Inc. and Moderna Inc., according to data from the Centers for Disease Control and Prevention. 

Novavax’s vaccine differs from Pfizer and Moderna’s vaccines by mimicking the protein the coronavirus uses to enter cells, instead of using mRNA technology. Novavax also has shots for the flu, respiratory syntical virus and other coronaviruses like SARS and MERS in its pipeline, each in various stages of clinical trials.

Its agreement with the UK initially called for 1 million doses and the possibility of an additional 15 million contingent on government approval, according to the filing. Novavax said it didn’t receive approval by its Nov. 30 deadline, and so would be obligated to repay $112.5 million and supply only 7.5 million doses. The company has until Nov. 30 of next year to gain approval from the UK’s vaccine committee for the rest of its supply.

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