Mercer Advisors Buys AI Tax Firm Fifteenth

The wealth manager is expanding its tax services for tech executives and employees with the purchase of San Francisco-based Fifteenth.

Updated on Nov. 5, 2026 in Financial Planning

Mercer Advisors Buys AI Tax Firm Fifteenth

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Mercer Advisors, a wealth manager with about $114 billion in client assets, has acquired Fifteenth, an AI-native tax and accounting firm based in San Francisco. The financial terms of the deal were not disclosed.

Why it matters

More than half of Mercer's ultra-high-net-worth clients who join want tax services, reflecting rising wealth complexity and a wave of executive equity and liquidity events. The acquisition positions Mercer to offer more integrated tax and wealth planning across the United States.

Mercer Advisors reports about $114 billion in client assets across 120 national locations, and more than half of its ultra-high-net-worth clients who join want tax services. The acquisition's financial terms were not disclosed, so its cost relative to Mercer's size remains unknown.

The players

Mercer Advisors

Mercer Advisors is a Denver-headquartered wealth management firm with about $114 billion in client assets and 120 national locations.

Fifteenth

Fifteenth is a San Francisco-based AI-native tax and accounting firm that serves Silicon Valley tech executives and employees.

The details

Fifteenth clients connect their financial accounts to its platform so tax management can be handled automatically, and its services cover stock options, tender offers, liquidity events and multi-entity filings. Mercer's Aspen 2.0 platform, launched about three months before the deal, integrates with custodians including Schwab, Fidelity, Raymond James and Goldman Sachs.

Mercer launched its Aspen 2.0 AI-enhanced wealth platform about three months before the acquisition.
Mercer announced the acquisition of Fifteenth on November 5, 2026.
Tax professionals are expected to reach about 12.5% of Mercer's staff by the end of 2026.

Market Dynamics

The acquisition extends Mercer's Aspen 2.0 AI-enhanced wealth platform, launched about three months earlier, by adding dedicated tax capabilities to its wealth offerings. It reflects a broader push by wealth managers to bundle AI-driven tax planning with investment advice as executive equity compensation grows more complex.

Investors with stock options, tender offers or other liquidity events may find integrated tax and wealth planning more accessible as wealth managers add AI-driven tax services. The change matters most for high-net-worth clients whose tax situations span multiple entities and accounts.

The takeaway

Investors with complex equity compensation may benefit from asking whether their wealth manager can coordinate tax planning with investment decisions. Integrated planning can help track liquidity events and multi-entity filings in one place.