Duo Security, founded in 2010 by Jon Oberheide and Dug Song, raised $120M in venture funding before its acquisition, including a $70M Series D at a $1.17B valuation. The Ann Arbor–based company developed MFA, SSO, and device-trust solutions for enterprises, focusing on secure, user-friendly access across cloud and on-prem apps. Funding enabled global sales expansion, product growth, and integrations. Key investors included Benchmark, Google Ventures, and Meritech Capital.