The vaccine maker's shares plunged more than 15% to $101.01, taking the company's market value to $38.71 billion. It had peaked at nearly $200 billion at the height of the COVID pandemic in August 2021.
Moderna said the full-year forecast cut was also due to potential revenue deferrals for some international COVID sales into 2025 and an increasingly competitive environment for COVID and RSV vaccines in the U.S.
The company had previously said it expected roughly $4 billion in sales for the year, which was already the lowest figure for annual revenue since it launched its COVID vaccine in late 2020 - the company's first commercial product.
Moderna said it now expects to make between $3 billion and $3.5 billion in sales for the year.
International revenue deferrals were one of the biggest factors in the $500 million range Moderna gave in its new 2024 sales forecast, Chief Financial Officer James Mock said in an interview.
During a conference call with analysts, CEO Stephane Bancel said the company expects COVID vaccine sales in the EU to also be low over the next two years, limited by Pfizer's (PFE.N) contract with the region, which ends in 2026.
Bancel said they are in discussions with European countries interested in providing COVID vaccine options in addition to the Pfizer/BioNTech (22UAy.DE) shot.
Mock told Reuters the company was still in discussions with the EU over 2024.
"Given where we are in the season combined with where we are in the budget season for many countries and their existing supplies, we feel there's a very low probability that we'll have very much (EU) sales in 2024," he said.
The company is also assuming U.S. COVID vaccination rates for the autumn campaign with updated shots will be similar to last year's.
Moderna has been banking of revenue from newer mRNA shots, including its RSV vaccine mRESVIA and an experimental COVID-flu combination vaccine.
Jefferies analyst Michael Yee in a research note said the new forecast means the company's net loss and cash burn - already at levels that concern investors - would increase.
The company said it expects to have $9 billion in cash at the end of this year, down from $13.3 billion at the end of 2023, and to have $6 billion to $7 billion at the end of 2025.
Analysts had forecast sales of $370 million for mRESVIA, Moderna's second product which won U.S. approval in late May, for this year. Shipments started last month but it is expected to lag RSV shots from Pfizer (PFE.N) and GSK (GSK.L).
Sales of Moderna's Spikevax COVID-19 vaccine were $184 million for the quarter, down 37% on the previous year but well ahead of analysts' average estimates of $66.42 million.
Moderna reported a net loss of $1.3 billion, or $3.33 per share, for the second quarter. Analysts had expected a loss of $3.39 per share.
