Sierra Space, the subsidiary of private aerospace contractor Sierra Nevada Corporation, is finalizing a raise of nearly $300 million, CNBC has learned.

The fundraising round values the space company at about $5 billion, according to two anonymous sources familiar with the transaction. Sierra Space expects to announce the successful raise within the coming week.

The leading investors in Sierra Space’s equity round are MUFG, Kanematsu, and Tokio Marine, with significant participation from existing investors and insiders. The deal is being advised by Citigroup.

Two years ago, Sierra Space raised $1.4 billion at a $4.5 billion valuation from investors including General Atlantic, BlackRock, AE Industrial Partners, Coatue, and Moore Strategic Ventures.

CNBC reached out to Sierra Space for comment on the funding but did not receive a response.

The fresh infusion of funds comes as Sierra Space focuses on the development of its Dream Chaser spaceplane.

The Dream Chaser, a reusable vehicle designed to deliver cargo and eventually crew to low Earth orbit, has been in development for several years. Resembling a miniaturized NASA Space Shuttle, it is built to launch on top of a traditional rocket and land on a runway like an airplane.

The initial launch of the Dream Chaser was initially planned for late last year, but delays in the development of United Launch Alliance’s Vulcan rocket have pushed back the timeline. Sierra Space intends to launch the Dream Chaser on ULA’s second Vulcan mission, with the first Vulcan launch scheduled for the fourth quarter of this year.

Furthermore, Sierra Space is actively involved in the creation of a private space station. The company plans to launch a “pathfinder” demonstration mission of its LIFE (Large Integrated Flexible Environment) habitat in 2026.