The two companies were once embroiled in a trade secret theft lawsuit. Now, Wisk is being absorbed into Archer.

Archer Aviation is buying three of Boeing’s aerospace subsidiaries: autonomous air-taxi developer Wisk Aero, military drone maker Insitu, and airspace-software firm SkyGrid. The deal also hands Boeing a stake in Archer.

Investors loved it. Archer (ACHR) stock jumped more than 20% on Monday, and the acquisition instantly turns a pre-revenue eVTOL startup into a company with a profitable defense business behind it.

It could accelerate Archer’s eVTOL plans.