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MASECO Asset Management Limited
MASECO Asset Management Limited was founded in London in 2009 by brothers James Sellon and Tim Sellon, both of whom had previously worked at American...
MASECO Asset Management Limited
MASECO Asset Management Limited was founded in London in 2009 by brothers James Sellon and Tim Sellon, both of whom had previously worked at American Express Financial Advisors. The firm was created to address a specific gap: expatriate American and Anglo-American families caught between two tax regimes and often underserved by domestic advisers. MASECO holds authorisation from the UK Financial Conduct Authority and is structured as a multi-family office rather than a single-family wealth manager. Investment strategy centres on multi-asset-class portfolios that blend global equities, fixed income, alternatives and cash — with asset allocation tailored to individual client risk profiles. The firm does not run concentrated sector or venture plays; it operates a diversified, long-only approach designed for capital preservation and tax-efficiency across both US and UK accounts. Portfolio companies and direct co-investments are not public, as the model emphasises fund vehicles and separately managed accounts. Geographically, the firm focuses on UK-based clients with US ties, occasionally extending to other European jurisdictions. The team size and total AUM are not disclosed publicly. MASECO maintains a single office in London, with no confirmed additional locations. The firm runs its own philanthropic advisory service, helping clients structure charitable giving through US donor-advised funds and UK vehicles, though no separate philanthropic foundation is linked to the firm itself. Structurally, MASECO differentiates itself through its dual-qualification requirement: advisers must hold both US and UK regulatory credentials, enabling them to advise on cross-border estate planning, trust structures, and retirement accounts. This regulatory posture — rare in the London wealth market — creates a client moat based on compliance expertise rather than asset size.
General information
Firm type
Multi Family Office
Year founded
2009
AUM
Undisclosed
Location
Region
Europe
Country
United Kingdom
City
London
Corporate office
London, United Kingdom
Principals
James Sellon
Co-Founder and Managing Director
Tim Sellon
Co-Founder and Managing Director
Sector focus
Frequently asked questions
Who runs investment decisions at MASECO?
Investment decisions are led by co-founders James Sellon and Tim Sellon, who set the firm’s strategic asset allocation. The discretionary portfolio management team executes allocations within the multi-asset framework designed by the co-founders. MASECO outsources some asset-class implementation via Dimensional Fund Advisors and other institutional fund managers.
How is MASECO structured as a multi-family office?
MASECO is a fee-only RIA and multi-family office, not a single-family office. It advises multiple unrelated families, each receiving customised wealth plans. In 2023 the firm transitioned to 100% employee ownership via an Employee Ownership Trust (EOT), which the co-founders described as a succession vehicle that aligns the firm with client longevity (per firm communication, May 2023).
What is MASECO’s known investment philosophy?
The firm follows a multi-asset, globally diversified approach with a tilt toward long-only, tax-efficient investing. It avoids direct private equity or venture capital — instead using public equities, investment-grade and high-yield bonds, and alternative funds such as real estate and infrastructure. The primary focus is on capital preservation and consistent income across market cycles.
Does MASECO maintain philanthropic structures?
MASECO offers advisory services for donor-advised funds and charitable trusts, but the firm does not operate a separate philanthropic foundation. Its charitable advisory practice helps clients with both UK and US tax-efficient giving, including Gift Aid, CAF accounts, and DAFs sponsored by US-based organisations.
Where does the underlying client wealth come from?
Client wealth is not concentrated in a single industry. MASECO serves business owners, lawyers, bankers, entertainers, and corporate executives — all with a common need: a US–UK cross-border financial strategy. The wealth origins are as diverse as the client base, and no particular sector is dominant.
What is MASECO’s known posture on co-investments alongside external GPs?
MASECO does not publicly participate in direct co-investments or club deals with external GPs. Its investment approach relies on pooled vehicles and separately managed accounts, with no disclosed direct equity positions in private companies. The firm has not reported co-investment activity in any public filing or announcement.
How does MASECO source proprietary deal flow?
MASECO is not a deal-sourcing firm. It does not originate private-market opportunities or claim proprietary deal flow. Investment offerings are sourced through established institutional fund relationships and open-architecture platforms, with no evidence of exclusive access to private placements or primary-issuance allocations.
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