FILE PHOTO: The headquarters of biopharmaceutical company BioNTech are seen in Mainz, Germany July 31, 2018. REUTERS/Ralph Orlowski

(Reuters) - BioNtech SE, Europe’s largest unlisted biotech firm by staff numbers, said on Tuesday that it planned to raise up to $303.6 million in an initial public offering in the United States.

The company expects its offering of about 15.2 million American depositary shares, including underwriters' option, to be priced between $18 and $20, BioNtech said in a regulatory filing. (here).

At the top end of the price range, the company could be valued at $4.59 billion, nearly double its valuation in January last year, when it had raised $270 million.

The German biotech company competes with Massachusetts-based Moderna MRNA.O and Belgium's eTheRNA in the race to develop mRNA therapies.

Last year, Pfizer PFE.N agreed to pay BioNtech up to $425 million to develop more effective influenza shots and also acquired a small stake in the company.

BioNtech posted a loss of 48 million euros ($52.77 million) in 2018, compared with a loss of 85.7 million euros a year earlier.

The company said it expects to use proceeds from the offering for general corporate purposes and may also use it to acquire or invest in complementary technologies and products.

J.P. Morgan, BofA Securities, UBS are among the underwriters of the IPO.