Maravai rejected the $42 per share all-cash offer from Goettingen, Germany-based Sartorius earlier this month as inadequate, the sources said. It is not clear whether Sartorius will return with a new offer or whether Maravai will attract acquisition interest from other laboratory equipment and supplies providers.

The sources requested anonymity because the matter is confidential. A Sartorius spokeswoman declined to comment, while Maravai representatives did not respond to requests for comment.

Maravai shares rallied on the news and ended trading in New York on Friday up 11% at $37.11.

Maravai makes reagents used in the production of mRNA vaccines, including the one developed by Pfizer Inc and BioNTech SE against COVID-19.

Its shares soared after it listed in the U.S. stock market in 2020, providing a lucrative exit for private equity firm GTCR, which had invested in the company in 2016. GTCR remains Maravai’s biggest shareholder with a minority stake and has representatives on the company’s board, according to Refinitiv data.

A GTCR spokesman did not respond to a request for comment.

Maravai shares are down 40% from their August 2021 high, as investors fret over whether the subsiding COVID-19 pandemic will weigh on the company’s business. Maravai said on Wednesday it continued to see strong demand for its reagents and forecast revenue growth of 15% to 20% in 2022.

Sartorius provides equipment and supplies to laboratories performing research and quality control at pharmaceutical companies and research institutes, and also makes products for use in the production of medications and vaccines. It has a market value of 27.6 billion euros ($31 billion).

(Reporting by Greg Roumeliotis in New YorkAdditional reporting by Krystal Hu in Beijing and Anirban Sen in BangaloreEditing by Leslie Adler and Diane Craft)

By Greg Roumeliotis