Shares fell 7 percent in premarket trading Thursday and 17 percent by mid-morning. Through Wednesday’s close, Moderna shares have fallen about 20 percent this year.

Moderna spokesman Chris Ridley said the company, which employs about 6,000 people worldwide, does not plan any layoffs.

The company is slowing its pace of research into new treatments, partly due to recent commercial challenges, and on Thursday it also pushed back its goal of breaking even from 2026 to 2028.

Last month, the company cut its full-year revenue expectations after reporting low sales of its COVID vaccine in Europe and increasing competition in the U.S., leading to a disappointing launch of its new RSV vaccine.

The company sells two products – a vaccine against COVID and one against RSV. It forecast sales of between $2.5 billion and $3.5 billion next year. This year, sales are expected to be between $3 billion and $3.5 billion, below the previous forecast of about $4 billion.

“We’re still dealing with a market of uncertainty,” Jamey Mock, Moderna’s chief financial officer, said in an interview. “We hope that will calm down this year, but we have to be prepared for vaccination rates to continue to decline.”

Mock said the research and development cuts were a sign that the company was “exercising financial discipline.”

Moderna has had to cut its R&D budget in part because clinical trials were successful and later studies require more money, he said. Moderna expects to have 10 products approved in the next three years.

“We recognize that we need to slow down because there is a huge amount of important medicines that need to be approved right now,” Moderna President Stephen Hoge said in an interview.

The company is known for spending heavily on research and development, often more than its rivals relative to revenue. The spending was fueled by the belief that its mRNA technology could effectively treat and prevent a range of diseases, from flu to cancer. But the sharp decline in its COVID vaccine business is forcing the company to scale back some of its ambitions.

One of the company’s biggest hopes is its cancer program. Late last year, Moderna and its partner Merck & Co. announced that their melanoma vaccine helped prevent the recurrence of severe skin cancer for three years.

Moderna executives had hoped to seek faster approval based on data from that mid-stage trial. Moderna said initial feedback from U.S. regulators was “not supportive” and the company and Merck were focused on the late-stage trial.

The company announced that it plans to increase its investment in oncology research and development.

In addition, the company will no longer seek accelerated approval of its standalone flu vaccine. Instead, it will focus on filing for approval this year of its vaccine that combines both flu and Covid protection.

“We just believe it could become a bigger product with a bigger impact,” Mock said.

Jonathan Saltzman of the Globe contributed to this report.