San Mateo, CA — January 7, 2026 — Sunstone Partners, a growth-oriented private equity firm focused on AI- and technology-enabled services and software companies, today announced that Sean Lenahan has joined the firm as Head of Portfolio Operations.
In this role, Lenahan will lead Sunstone’s Portfolio Operations Group and partner closely with management teams across the portfolio to help accelerate growth, strengthen operational foundations, and support value creation initiatives including go-to-market execution, talent and organization, operational improvement, and M&A integration.
Lenahan brings deep experience scaling founder-led and growth-stage businesses. Prior to joining Sunstone Partners, he served as an Operating Partner at Bregal Sagemount, where he partnered with portfolio company leadership to accelerate growth and build operational scale. Earlier in his career, he was an Operating Partner at The Riverside Company’s growth equity fund, and he began his career as an engineer and management consultant before serving twice as CEO of global technology businesses through successful exits. Lenahan holds a B.S. from the U.S. Air Force Academy and an MBA from the Wharton School of the University of Pennsylvania.
Arneek Multani, Co-Founder and Managing Partner at Sunstone Partners, said: “Sean is a builder with a track record of helping founder-led businesses professionalize, scale, and execute through critical growth inflection points. As we continue to invest in operational capabilities that help our portfolio companies accelerate organic growth and pursue strategic acquisitions, we’re excited to welcome Sean and the experience he brings to our team and our founders.”
Lenahan added: “I’m thrilled to join Sunstone Partners and collaborate with the firm’s portfolio company leadership teams. Sunstone has built a reputation for being a founder-first partner, and I’m excited to help companies translate strong market opportunity into repeatable execution—investing in people, technology, scalable processes, and operating discipline to drive novel solutions for our companies’ customers, sustainable growth and market leadership.”
About Sunstone Partners
Sunstone Partners is a growth-oriented private equity firm that invests in AI- and technology-enabled services and software companies. The firm seeks to partner with exceptional entrepreneurs, often as their first institutional capital partner, to help accelerate organic growth and fund acquisitions. Founded in 2015, Sunstone Partners has $1.7 billion of committed capital under its first three funds and invests in majority and minority transactions.
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