What is a family office?
A family office is a private company that manages the investments, wealth, and administrative affairs of one or more affluent families. It exists to preserve and grow a single fortune across generations, combining investment management with estate planning, tax, philanthropy, and governance under one roof.
A family office is a private company that manages the investments, wealth, and administrative affairs of one or more affluent families. Its purpose is to preserve and grow a single fortune across generations. A full family office combines investment management with estate and tax planning, philanthropy, education for the next generation, and day-to-day administration, functions that a wealthy family would otherwise buy piecemeal from banks, advisers, and lawyers.
The modern family office is often traced to the office John D. Rockefeller established in the 1880s to manage his fortune. The model spread as private wealth grew, and it accelerated after 2000 as technology and finance created a new generation of billionaires who wanted control, privacy, and direct access to deals. Today a family office can be a two-person outsourced setup or a 100-person institution that rivals a mid-size asset manager.
In private markets, the family office matters because it is patient, discretionary capital. A family office answers to a family rather than to an investment committee, a consultant, or a fund's limited partners. That independence lets it hold assets for decades, concentrate in sectors it knows, and move on a direct deal in weeks. For fund managers, family offices are among the most sought-after and hardest-to-map limited partners in the market.
Types of family office
Single-family office (SFO).
A private company that serves one family. It employs dedicated staff and is usually exempt from SEC registration under the family office rule. SFOs typically become cost-effective around $100M to $250M in investable assets and scale to institutional size above $1B.
Multi-family office (MFO).
A firm that serves several unrelated families, sharing staff and infrastructure to lower the cost for each. Because it advises clients beyond one family, an MFO usually registers as an investment adviser and files Form ADV, which makes it far more discoverable than an SFO.
Virtual or outsourced family office.
A lean model where a small team coordinates external advisers rather than employing them. It suits families below the threshold for a fully staffed office, or those that prefer to keep headcount light while retaining a single point of coordination.
Embedded family office.
An investment function that sits inside a family's operating business, sharing the company's finance and legal staff. Common for first-generation wealth, it often spins out into a standalone single-family office once the family exits or diversifies.
How much wealth does a family office need?
There is no legal minimum. The threshold is economic: the cost of dedicated staff has to be justified by the size of the fortune. These bands are directional, not rules.
| Investable wealth | Typical structure |
|---|---|
| Under $100M | Virtual or outsourced office, or a client of a multi-family office |
| $100M–$250M | Lean single-family office, or a multi-family office relationship |
| $250M–$1B | Staffed single-family office with a defined allocation program |
| $1B–$5B | Institutional single-family office with direct-deal and co-investment activity |
| $5B+ | Multi-strategy office with in-house teams, rivaling a mid-size institution |
Thresholds vary with the complexity of the family, its operating businesses, and its appetite for direct investing. Many families run an outsourced model well above these levels by choice.
Family offices and SEC registration
A qualifying single-family office is exempt from registering as an investment adviser. The SEC family office rule (Rule 202(a)(11)(G)-1 under the Investment Advisers Act of 1940), adopted after the Dodd-Frank Act removed the old private-adviser exemption, excludes an office that serves only family clients, is wholly owned and controlled by the family, and does not hold itself out to the public as an investment adviser.
That exemption is why single-family offices file no Form ADV and leave a thin public footprint. A multi-family office serves clients beyond one family, so it generally cannot use the exemption and registers as an investment adviser instead. The result is a practical asymmetry: multi-family offices are visible through public filings, while single-family offices must be identified through the edges of the public record.
How family offices invest
Family offices invest across the full spectrum of public and private assets, but the private side is where they stand out. A typical office allocates to private equity and venture funds, direct and co-investments, real estate, private credit, public equities, and increasingly to sector themes the family understands from its operating roots. Many hold a large concentrated position in the business that created the wealth, then diversify around it.
Two traits define family office behavior as a limited partner. The first is time horizon. Without redemption pressure or a fund life, an office can underwrite a decade-long hold that an institutional LP cannot. The second is direct-deal appetite. As offices add staff and conviction, they move from fund commitments toward direct investments and co-investments, often preferring to put capital to work alongside a manager rather than only inside a fund.
Wealth origin shapes strategy more than any other factor. A technology-founder office leans venture and growth. An industrial or real-estate fortune leans real assets and buyout. A trading fortune often runs strategies in-house. Reading that origin is the starting point for any manager trying to understand how a given office will allocate.
What a family office does beyond investing
Estate and tax planning.
Structuring trusts, entities, and cross-border holdings to transfer wealth efficiently and hold it across generations.
Philanthropy.
Running a family foundation or donor-advised strategy, often visible publicly through IRS Form 990 filings.
Governance and succession.
Building the family constitution, education for the next generation, and the decision rights that keep a fortune intact through transition.
Administration and reporting.
Consolidated reporting, bill pay, cash management, and the concierge functions that a large private balance sheet requires.
Risk and security.
Insurance, cyber and physical security, and the privacy controls that ultra-high-net-worth families treat as a priority.
Direct-deal sourcing.
Building networks and diligence capacity to originate and evaluate direct investments, the function that most distinguishes a mature office.
Family offices — common questions
What is a family office in simple terms?
How much money do you need for a family office?
What is the difference between a single-family office and a multi-family office?
Do family offices have to register with the SEC?
How do family offices invest?
How many family offices are there?
What is a virtual family office?
Dig deeper
Single-Family Offices (SFOs)
How SFOs allocate as LPs, and how to reach them.
Multi-Family Offices (MFOs)
The Form ADV footprint and approved-list gate.
Family office database
9,000+ family offices by type, AUM band, and geography.
Altss for family offices
How allocator teams use Altss for peer research.
Data methodology
How Altss sources and verifies family office data.
Family offices by city and region
Coverage across 37 metros and 6 regions.
Authoritative sources
The regulatory framework behind the family office structure comes from primary sources.
SEC — Family Offices final rule (Release IA-3220)
The SEC's 2011 rule defining the family office exclusion under the Investment Advisers Act.
eCFR — Rule 202(a)(11)(G)-1, Family offices
The codified text of the family office rule.
SEC — Investment Adviser Public Disclosure (IAPD)
Form ADV filings for registered advisers, including most multi-family offices.
Track the family office universe.
Altss maps 9,000+ family offices with verified decision-makers where publicly observable. Book a demo and see the coverage for your strategy.