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William A. Oneil

MFS INSTITUTIONAL ADVISORS
Boston, MA 02199-7618
Some features on this profile are disabled
CRD#: 6983697
WO

Professional summary

William Arthur Oneil, who also goes by Billy O'neil, William Arthur O'neil, William Arthur Oneil, is a registered financial advisor currently at MFS INSTITUTIONAL ADVISORS INC. located in Boston, Massachusetts and MFS FUND DISTRIBUTORS, INC. located in Boston, Massachusetts.

William is registered as an IAR (Investment Advisor Representative) and RR (Registered Representative) and started their career in finance in 2019. William has worked at 7 firms and has passed the Series 66, Series 63, Series 7TO, Series 6TO and SIE exams.

Question & Answer

Are you a "fiduciary"?
Yes

Aliases

Billy O'neil | William Arthur O'neil | William Arthur Oneil

Other business activities

Outside business activity is any business or activity undertaken by an advisor that is outside the scope of their relationship with their firm (e.g., consulting services, real estate, freelance work, teaching, etc.). Investors should stay informed about these activities to ensure no conflicts of interest.
The advisor shows no other business activity.

Blog Corner

CRS (Client Relationship Summary) - RIA

Click below to view William Arthur Oneil's CRS (Customer Relationship Summary).
CRS (Customer Relationship Summary)

Certified licenses

Advisors may have various certifications and credentials from different organizations. AdvisorCheck highlights these seven certifications - AIF®, CFP®, ChFC®, CFA, CLU®, CIMA®, CPWA®
None

Experience

Current

April 10, 2026 - Present

MFS INSTITUTIONAL ADVISORS INC.

Office #1: 111 Huntington Avenue, Boston, MA 02199-7618
RIA
CRD#: 107144
Boston, MA
Current

March 10, 2026 - Present

MFS FUND DISTRIBUTORS, INC.

Office #1: 111 Huntington Avenue, Boston, MA 02199
BD
CRD#: 31052
Boston, MA
Past

May 25, 2022 - May 28, 2024

PUTNAM INVESTMENT MANAGEMENT, LLC

RIA
CRD#: 106629
BOSTON, MA
Past

May 19, 2022 - May 28, 2024

PUTNAM RETAIL MANAGEMENT LIMITED PARTNERSHIP

BD
CRD#: 7325
Boston, MA
Past

January 4, 2021 - May 6, 2022

AMUNDI ASSET MANAGEMENT US, INC.

RIA
CRD#: 107719
BOSTON, MA
Past

June 9, 2020 - December 31, 2020

AMUNDI PIONEER INSTITUTIONAL ASSET MANAGEMENT, INC.

RIA
CRD#: 138756
BOSTON, MA
Past

January 7, 2019 - May 6, 2022

AMUNDI DISTRIBUTOR US, INC.

BD
CRD#: 24497
BOSTON, MA

Primary Firm SEC Registration

This SEC-registered firm can serve clients nationwide. Some states may require the firm to submit a notice filing if the firm has more than 5 clients or a physical office there. You can view these state-level filings under the section titled "State Registrations and Notice Filings".
MI
MFS INSTITUTIONAL ADVISORS INC.
MFS INSTITUTIONAL ADVISORS INC.

CRD#: 107144 / SEC#: 801-46433

RIA
Registered Investment Advisory firm - (5/6/1994 Approved)

State Registrations and Notice Filings

Listed states reflect where the advisor is authorized to serve clients under state regulations.

IAR
means the advisor is registered as an Investment Advisor Representative in this state and is authorized to provide investment advice to clients there.
RR
indicates the advisor is registered as a Registered Representative in this state, allowing them to offer securities such as stocks, bonds, and mutual funds through a broker-dealer.

Visual representation of state registrations

RR
Massachusetts
(3/10/2026)
IAR
Massachusetts
(4/10/2026)

Exams

State Security Law Exam
RR
IAR
Series 66
Date: 6/3/2020
Uniform Combined State Law Examination
State Security Law Exam
RR
Series 63
Date: 6/28/2019
Uniform Securities Agent State Law Examination
General Industry/Product Exam
RR
Series 7TO
Date: 4/25/2019
General Securities Representative Examination
General Industry/Product Exam
RR
Series 6TO
Date: 1/7/2019
Investment Company Products/Variable Contracts Representative Examination
General Industry/Product Exam
RR
SIE
Date: 12/5/2018
Securities Industry Essentials Examination
SRO Registrations
RR
FINRA

Current Firm

MI
MFS INSTITUTIONAL ADVISORS INC.
MFS INSTITUTIONAL ADVISORS INC.

CRD#: 107144 / SEC#: 801-46433

RIA
Registered Investment Advisory firm - (5/6/1994 Approved)
PREMIUM
Stay ahead of every change that matters. Proactive intelligence on your advisors, before issues escalate.
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Catch Firm Red Flags SoonerCatch leadership changes and disclosures early, before issues escalate.
Trends, Not Just SnapshotsMonitor firm stability metrics like AUM and advisor ratios over time.

Contact information

Main Address
111 Huntington Avenue, Boston, MA 02199-7618
Mailing Address
Phone number
(617) 954-5000
Established
Firm type
Fiscal year end
# of Employees
1,331

SEC notice filing (53 States and Territories)

Blank US states mapAlaskaHawaiiAlabamaArkansasArizonaCaliforniaColoradoConnecticutDelawareFloridaGeorgiaIowaIdahoIllinoisIndianaKansasKentuckyLouisianaMassachusettsMarylandMaineMichiganMinnesotaMissouriMississippiMontanaNorth CarolinaNorth DakotaNebraskaNew HampshireNew JerseyNew MexicoNevadaNew YorkOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVirginiaVermontWisconsinWest VirginiaWyoming

Documents

Customer Relationship Summary (CRS / SEC)Latest Form ADV

Part 2 Brochures

MFSI BROCHURE (1/20/2026)
SUMMARY OF MATERIAL CHANGES (3/31/2025)

Regulatory assets under management

Total Number of Accounts10,260
AUM (Assets Under Management)$ 111,845,233,320

Red Flags

Disclosures can be potential red flags, including customer disputes, regulatory fines, employer terminations, bankruptcies, judgments, liens, or certain criminal activities.

Check for any disclosures as part of your thorough research when choosing an advisor.

Company Information

MFS INSTITUTIONAL ADVISORS INC.

CRD#: 107144Boston, MA 02199-7618

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