(Reuters] – Rolls-Royce’s plans to develop electric aero engines as well as greener fuel options puts doubts about its prospects in civil aviation, J.P. Morgan said Tuesday.

In its first rating update since March 2013, the U.S. bank lowered Rolls-Royce to “underweight” instead of “equal-weight”. This was the U.S. banks’s first rating adjustment. It stated that Rolls-Royce’s decision implied low confidence in the largest unit in the company and may increase execution risks over the next few years.

British Aero-Engine Maker’s stock plunged 5% after the warning, putting pressure on a company that has already seen 25% of its value fall this year.

Rolls-Royce was devastated by 2020’s COVID-driven crash in air travel. The company has since tried to fix its finances by cutting over 1 billion pounds ($1.30billion) of costs. Recently, Rolls-Royce stated that 2022 will see modest cash flow as customers fly again.

Additionally, the company is focusing on developing more carbon-efficient hybrid, electric, or hydrogen-powered engines that could replace existing ones.

However, there has been some skeptical about these efforts.

David Perry, J.P. Morgan analyst said that “most aviation experts think it won’t be possible to build a large commercial airplane that can be powered by electricity for at least many decades.”

Greener options are part of the reporting segment “New Markets”, which also contains a project to construct a small modular reactors unit for the company, which may eventually replace sustainable aviation fuel. Britain and Qatar have backed the project.

According to Refinitiv Eikon, Perry’s recommendation of Rolls-Royce as a “sell” is supported by four other analysts. Meanwhile, 10 brokerages are neutral on the company.

($1 = 0.7684 pounds)