Abstract Defense contractors play an essential role in US security operations. Among other responsibilities, contractors manufacture arms, manage logistics, analyze intelligence, and carry out cybersecurity operations. Historically, defense contractors were either publicly traded corporations or privately owned companies. The past two decades, however, have seen a major shift in the ownership structure of the US defense industry. Private equity firms—once niche actors in the US national security marketplace—have carried out over 1,500 deals involving defense contractors since 2000. This study employs a mixed-methods research design to assess the effects of private equity investment on the financial stability of the US defense industry. Using data on over 8,000 defense contractors, the inquiry finds that contractors with private equity backing experience bankruptcy at higher rates than contractors with no prior private equity investment. In addition, the study evaluates private equity activity in the military satellite services market—a field of growing importance in the strategically important domain of outer space. The inquiry’s findings have notable international security implications. Given the US’ role as a lynchpin in numerous alliances around the world, higher rates of bankruptcy among defense contractors have the potential to affect the security of the United States and its allies.