Fiduciary standard vs. suitability standard (and Reg BI)
TL;DR. The fiduciary standard applies to registered Investment Advisers under the Investment Advisers Act of 1940 and requires an advisor to act in the client's best interest at all times. The suitability standard applied to broker-dealers until 2020 and required only that a recommendation be "suitable" given what the broker knew about the client. In 2020, the SEC replaced suitability with Regulation Best Interest (Reg BI) — a middle ground that is stricter than suitability but weaker than the fiduciary standard. Knowing which one applies to your advisor is how you know what legal protection you have.
What the fiduciary standard actually requires
Under the Investment Advisers Act of 1940 §202(a)(11), any person who, for compensation, advises others on securities is an "investment adviser" and owes the client a fiduciary duty. The Supreme Court confirmed the duty in SEC v. Capital Gains Research Bureau, 375 U.S. 180 (1963).
The duty has two parts:
- Duty of loyalty. Put the client's interests above the adviser's. Disclose every material conflict — not just the egregious ones.
- Duty of care. Provide advice with the skill, prudence, and diligence a reasonable professional would use.
The key word is "always." The fiduciary standard applies to every recommendation, including the ones where the adviser could technically get away with less.
What the old suitability standard required (pre-2020)
Until June 2020, broker-dealers were governed by FINRA Rule 2111 — the suitability rule. The broker had to have a "reasonable basis to believe" that a recommendation was suitable given the client's investment profile.
"Suitable" is not the same as "best." Two mutual funds might both be suitable for a 55-year-old saving for retirement. If Fund A pays the broker a 1% commission and Fund B pays 5%, and both are "suitable," suitability did not require the broker to recommend Fund A.
This is the gap the fiduciary standard is designed to close.
What Regulation Best Interest (Reg BI) added in 2020
In June 2020, the SEC adopted Regulation Best Interest (Reg BI), which replaced the suitability standard for broker-dealer recommendations to retail customers. Reg BI requires that a recommendation be in the customer's best interest at the time it is made, considering reasonably available alternatives and the customer's investment profile.
Reg BI is an improvement. It is not a fiduciary standard. Key differences:
| Fiduciary (IA) | Reg BI (BD) | |
|---|---|---|
| Applies to | Investment Advisers | Broker-dealers |
| Scope | Ongoing relationship, all advice | Point-in-time recommendations |
| Conflicts | Must be disclosed AND mitigated | Must be disclosed |
| Monitoring duty | Continuous | Only when making recommendations |
| Enforcement | Adviser's own fiduciary duty + SEC | FINRA + SEC |
| Requires best recommendation? | Yes (tied to duty of loyalty) | Requires "in best interest," not "best available" |
The words "best interest" in Reg BI do not mean what they mean in the fiduciary standard. They mean the recommendation must consider cost, risk, and reasonably available alternatives — but a broker can still recommend a higher-commission product if they can defend the choice.
Why "best interest" and "best for you" are different
This is the single most important sentence in this article: a recommendation can be in your best interest without being the best available to you.
Reg BI's "best interest" is a process standard. Did the broker consider alternatives? Did they have a reasonable basis for the recommendation? Did they disclose conflicts?
The fiduciary standard goes further. It requires the adviser not just to make a defensible recommendation, but to recommend what the client's situation actually demands — even when it means less revenue for the adviser.
How to tell which standard your advisor owes you
Three tests, in order:
- Registration type. If they are registered as an Investment Adviser Representative on IAPD, the fiduciary standard applies on their advisory work. If they only appear on FINRA BrokerCheck, Reg BI applies.
- Compensation type. Fee-only compensation is the structural hallmark of the fiduciary standard. Commission-earning on products is the structural hallmark of Reg BI.
- Written confirmation. Ask the advisor in writing: "Are you acting as a fiduciary on every recommendation you make to me, at all times, with no exceptions?" A Reg BI–only broker will not answer yes without qualification.
For a step-by-step walkthrough, see Is my financial advisor a fiduciary?.
The dual-registered problem
About half of registered advisors in the United States are "dual-registered" — both an Investment Adviser Representative and a broker-dealer representative. They legally wear two hats. When they're giving you "advice" the fiduciary standard applies. When they're "effecting a transaction" Reg BI applies.
In practice, the line between the two activities is blurry, and disputes about which hat was being worn at a specific moment are how customer arbitration cases get complicated. If you want a clean fiduciary relationship, hire a fee-only adviser whose firm is registered only as an RIA.
What the historical record shows
The SEC studied the suitability standard in a 2011 report to Congress (Study on Investment Advisers and Broker-Dealers, Section 913 of Dodd-Frank). It found that retail investors were broadly confused about which standard applied to their advisor — and that product sales motivated by commissions often led to worse outcomes for customers, even when the recommendations passed suitability.
That study kicked off nearly a decade of regulatory effort. The 2016 DOL Fiduciary Rule tried to apply a fiduciary standard to retirement accounts; it was vacated by the Fifth Circuit in 2018. Reg BI was the SEC's compromise in 2020.
The fiduciary standard exists because the suitability standard was demonstrably not enough.
Key takeaways
- Fiduciary standard: always acts in client's best interest. Applies to RIAs.
- Suitability standard (pre-2020): recommendation must be "suitable." Applied to broker-dealers.
- Reg BI (2020+): stricter than suitability, weaker than fiduciary. Applies to BDs.
- "Best interest" in Reg BI is a process standard, not a guarantee of the best option.
- Dual-registered advisors owe the fiduciary standard only on advice, not on product sales.
Sources
- Investment Advisers Act of 1940 §202(a)(11) — PDF.
- SEC v. Capital Gains Research Bureau, 375 U.S. 180 (1963).
- FINRA Rule 2111 (Suitability) — finra.org.
- SEC Regulation Best Interest, Release No. 34-86031 — final rule.
- SEC Study on Investment Advisers and Broker-Dealers (Section 913 of Dodd-Frank), January 2011.
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