Key Takeaways
- • Mercer Advisors, a national wealth management firm with $114 billion in client assets, has acquired Fifteenth, an AI-native tax and accounting firm focused on equity compensation and complex tax situations, according to a Business Wire release.
- • Fifteenth's proprietary AI platform is already serving more than 1,000 professionals, and its team includes tax talent from Big Four and other leading firms.
- • Tax professionals make up roughly one in 10 Mercer employees today and are expected to reach one in eight by the end of 2026, per the firm.
- • Mercer says more than half of its ultra-high-net-worth clients who join are seeking integrated tax capabilities, driven by executive equity and liquidity events at fast-growing companies.
- • The deal extends Mercer's family office model into earlier-stage tax planning ahead of IPOs, sales, and other liquidity events.
Summary
Mercer Advisors, Inc. announced the acquisition of Fifteenth, an artificial intelligence-native tax and accounting firm whose proprietary platform is built for equity compensation and complex tax situations, according to a Business Wire release dated November 5, 2026. Mercer describes itself as a national wealth management and financial planning firm, with $114 billion in client assets as of September 30, 2026, more than 120 locations, and 1,880-plus employees. The firm is majority owned by Oak Hill Capital, Genstar Capital, Atlas Partners and GIC.
Fifteenth's team brings tax expertise from Big Four and other leading firms, paired with its AI platform. The firm combines annual tax preparation with year-round planning for clients handling stock option exercises, tender offers, liquidity events and multi-entity filings, and it has a strong following among employees of Silicon Valley technology companies. Fifteenth CEO and Co-Founder Ankur Dahiya said the firm's tools already serve more than 1,000 professionals. Laura Moreno, Chief Tax Officer and Co-Founder of Fifteenth, said the combination of technology and experienced tax judgment would allow the firm to reach more clients at greater scale.
Mercer framed the deal as part of its broader strategy to deploy practical AI across its family office services, which include financial planning, tax planning and preparation, estate planning and investment management. Cynthia Loh, Chief Platform Officer of Mercer Advisors, said the firm expects the integration to meaningfully expand the capacity of its tax teams. Mercer said more than half of the ultra-high-net-worth clients joining the firm are seeking tax capabilities as part of a unified offering, and that tax professionals now represent roughly one in 10 employees, a share it expects to reach one in eight by year-end 2026. Daniel Gourvitch, President of Mercer Advisors, said Fifteenth fits the firm's partnership model of pairing technology with high-caliber professionals.
The acquisition also gives Mercer an earlier entry point into clients' equity compensation planning, supporting strategy ahead of a sale, IPO or other major liquidity event rather than only at filing time. Mercer noted that the deal also deepens tax support for a subset of its existing tax clients facing similar complexity. Financial terms of the transaction were not disclosed in the release.
Fifteenth's team brings tax expertise from Big Four and other leading firms, paired with its AI platform. The firm combines annual tax preparation with year-round planning for clients handling stock option exercises, tender offers, liquidity events and multi-entity filings, and it has a strong following among employees of Silicon Valley technology companies. Fifteenth CEO and Co-Founder Ankur Dahiya said the firm's tools already serve more than 1,000 professionals. Laura Moreno, Chief Tax Officer and Co-Founder of Fifteenth, said the combination of technology and experienced tax judgment would allow the firm to reach more clients at greater scale.
Mercer framed the deal as part of its broader strategy to deploy practical AI across its family office services, which include financial planning, tax planning and preparation, estate planning and investment management. Cynthia Loh, Chief Platform Officer of Mercer Advisors, said the firm expects the integration to meaningfully expand the capacity of its tax teams. Mercer said more than half of the ultra-high-net-worth clients joining the firm are seeking tax capabilities as part of a unified offering, and that tax professionals now represent roughly one in 10 employees, a share it expects to reach one in eight by year-end 2026. Daniel Gourvitch, President of Mercer Advisors, said Fifteenth fits the firm's partnership model of pairing technology with high-caliber professionals.
The acquisition also gives Mercer an earlier entry point into clients' equity compensation planning, supporting strategy ahead of a sale, IPO or other major liquidity event rather than only at filing time. Mercer noted that the deal also deepens tax support for a subset of its existing tax clients facing similar complexity. Financial terms of the transaction were not disclosed in the release.
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