
401(k) glossary
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Fiduciary & roles
3(38) fiduciary (investment manager)
Short definition
A 3(38) fiduciary is an investment manager, as defined in section 3(38) of ERISA, with discretion to choose and change a plan’s investments. It must be a registered investment adviser, bank or insurance company.
What a 3(38) fiduciary is
Section 3(38) of ERISA defines an “investment manager” as a fiduciary that has the power to manage, acquire or dispose of plan assets, that is a registered investment adviser, a bank or an insurance company, and that has acknowledged in writing that it is a fiduciary to the plan.
For a 401(k), a 3(38) manager typically selects the fund lineup and the default investment, monitors them and replaces funds when needed. It acts without asking the employer to approve each change.
Why it matters to employers
ERISA says that when an investment manager has been properly appointed, the plan’s other fiduciaries are not liable for the manager’s individual investment decisions. This is the largest transfer of investment responsibility available to an employer.
It is not a complete transfer. Appointing the manager is a fiduciary decision. You must choose the manager prudently, understand its fees and review its performance periodically. Keep a record of each review.
Example
An employer appoints a registered investment adviser as 3(38) manager under an investment management agreement. During the year the manager replaces an underperforming bond fund. The employer is told about the change and does not need to approve it. At its annual review, the employer checks the manager’s report against the plan’s investment policy statement and files the minutes.
Common mistakes
Assuming a 3(38) covers plan administration. Filings, notices and distributions are 3(16) duties.
Not having the written acknowledgment of fiduciary status.
Never reviewing the manager after appointment.
Assuming the manager is responsible for investments employees choose through a brokerage window. Usually it is not.
Basic Capital and this term
Basic Capital Advisors can serve as the 3(38) investment fiduciary for a plan’s fund menu; the service is optional and separate from recordkeeping.
Go deeper
Read the full employer guide related to: 3(38) fiduciary (investment manager)
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Sources
U.S. Code (govinfo.gov): 29 U.S.C. 1002 (ERISA section 3): Definitions (https://www.govinfo.gov/content/pkg/USCODE-2023-title29/html/USCODE-2023-title29-chap18-subchapI-subtitleA-sec1002.htm), retrieved 2026-11-11 U.S. Code (govinfo.gov): 29 U.S.C. 1105 (ERISA section 405): Liability for breach of co-fiduciary (https://www.govinfo.gov/content/pkg/USCODE-2023-title29/html/USCODE-2023-title29-chap18-subchapI-subtitleB-part4-sec1105.htm), retrieved 2026-11-11 U.S. Department of Labor, EBSA: Meeting your fiduciary responsibilities (https://www.dol.gov/agencies/ebsa/about-ebsa/our-activities/resource-center/publications/meeting-your-fiduciary-responsibilities), retrieved 2026-11-11
General information, not legal or tax advice.

