Marsh appoints Niall O’Sullivan as Mercer’s Global Chief Investment Officer
NEW YORK, April 20, 2026 ─ Mercer, a Marsh business (NYSE: MRSH) and a global leader in helping clients realize their investment objectives, shape the future of work, and enhance health and retirement outcomes for their people, today announced that Niall O’Sullivan will become Global Chief Investment Officer, effective May 1, 2026.
He succeeds Hooman Kaveh, who will assume the newly created role of Executive Chair for Mercer’s Investment Platform. Mr. O’Sullivan and Mr. Kaveh will report to Michael Dempsey, Mercer’s President for Investments and Retirement, and remain based in Dublin.
As Global Chief Investment Officer, Mr. O’Sullivan will lead the full range of Mercer’s investment capabilities, from research to investment solutions and performance, across traditional and alternative asset classes. He will also enable Mercer’s investment colleagues to operate effectively across the continuum of tools, advice and implementation and play an active role in integrating the investment expertise and capabilities gained from recent acquisitions. Going forward, all asset class teams will report to Mr. O’Sullivan.
“Niall’s deep knowledge of our investment business, passion for achieving strong investment outcomes for our clients, and ability to foster high-performing teams will position us strongly for the future,” said Mr. Dempsey. “Continuing to work together, both Niall and Hooman will help accelerate the integration of our expanding investment capabilities, scale our differentiated offerings, and deliver consistent, impactful outcomes for our clients.”
“It is an honor to lead Mercer’s global investment organization at this pivotal moment for institutional investors,” said Mr. O’Sullivan. “Mercer is well-positioned to partner with clients to help them make sense of market volatility and support their unique long-term objectives. I’m eager to work across our global and regional teams to innovate compelling investment offerings that will delight investors and enable scalable growth.”
In his new capacity, Mr. Kaveh will lead a number of key strategic initiatives, including a focus on M&A, integrating AI into Mercer’s investment processes, and providing custom training and development resources to help colleagues optimize Mercer’s expanding range of investment capabilities. He will continue to chair the Investment Governance Committee.
Mr. Dempsey added: “We greatly appreciate Hooman’s trusted counsel over the past twenty years and are pleased that our investment colleagues will continue to benefit from his leadership and experience during this next phase of growth for our business.”