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RIA / WealthAdvisordual registered (broker-dealer)10 years in industry

William Arthur ONeil

Advisor at MFS INSTITUTIONAL ADVISORS INC.

Boston, MA | BOSTON, MA

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Search this name across graphsid dfx:ria:02c999fe-77de-1219-76c3-88a07eb930cf

Data as of Sep 15, 2026 (this record's last observation) from federal regulator filings. Page built Sep 20, 2026, 6:44 AM UTC and rebuilt at most every 15 minutes.

Relationships: 4
Dated events: 2
On other graphs: 0
Observed: Jun 9, 2020 to Sep 15, 2026

Across DFX

This entity has not been resolved onto another DFX graph by a shared identifier. A name match elsewhere would be a candidate, never an identity, and none is recorded.

Facts

fact = as filed or announced; derived = computed by DFX; estimate = a band, never a point

Current firm: MFS INSTITUTIONAL ADVISORS INC.
Current firm class: other adviserderived
Book size: not publicno per-advisor AUM is published by the SEC, FINRA or IAPD, and DFX estimates none
Industry start: Aug 1, 2016earliest registration or exam on IAPD
Years in industry: 10derivedfrom the industry start date
Years at current firm: 0derivedfrom the current registration's begin date
Prior firms: 3
Current registrations: 1
Registered states: 1
Exams: S66|S63
First exam: Jun 28, 2019
First registration: Jun 9, 2020
Dual registered: yes, broker-dealer
Other names: WILLIAM ARTHUR ONEIL|BILLY O'NEIL|WILLIAM ARTHUR O'NEIL
IAPD individual key: 6983697

Registration history

registration spans on IAPD; the basis says whether the span is a current registration or a prior employment record

Firm	Class	Began	Ended	Current	Branch	Basis
MFS INSTITUTIONAL ADVISORS INC.	Other adviser	Apr 10, 2026	n/a	yes	Boston, MA\|BOSTON, MA	Current employment
PUTNAM INVESTMENT MANAGEMENT, LLC	Asset manager	May 25, 2022	May 28, 2024	no	BOSTON, MA	Previous registration
AMUNDI ASSET MANAGEMENT US, INC.	Former SEC adviser	Jan 4, 2021	May 6, 2022	no	BOSTON, MA	Previous registration
AMUNDI PIONEER INSTITUTIONAL ASSET MANAGEMENT, INC.	Former SEC adviser	Jun 9, 2020	Dec 31, 2020	no	BOSTON, MA	Previous registration

Moves

a move is two registration dates; a bulk corporate re-registration is typed BULK_TRANSFER and is not a move

From	To	Left	Joined	Gap, days	Kind	Move type
PUTNAM INVESTMENT MANAGEMENT, LLC	MFS INSTITUTIONAL ADVISORS INC.	May 28, 2024	Apr 10, 2026	682	Firm change after gap	Other
AMUNDI ASSET MANAGEMENT US, INC.	PUTNAM INVESTMENT MANAGEMENT, LLC	May 6, 2022	May 25, 2022	19	Firm change	Other
AMUNDI PIONEER INSTITUTIONAL ASSET MANAGEMENT, INC.	AMUNDI ASSET MANAGEMENT US, INC.	Dec 31, 2020	Jan 4, 2021	4	Bulk transfer	Other

Relationships

Registered with (4)

→ MFS INSTITUTIONAL ADVISORS INC.Registered adviserregistration: current employment
Apr 10, 2026 to presentfactForm ADV
→ PUTNAM INVESTMENT MANAGEMENT, LLCRegistered adviserregistration: previous registration
May 25, 2022 to May 28, 2024factForm ADV
→ AMUNDI ASSET MANAGEMENT US, INC.Registered adviserregistration: previous registration
Jan 4, 2021 to May 6, 2022factForm ADV
→ AMUNDI PIONEER INSTITUTIONAL ASSET MANAGEMENT, INC.Registered adviserregistration: previous registration
Jun 9, 2020 to Dec 31, 2020factForm ADV

Dated events

Occurred
May 28, 2024
Advisor changed firm
William Arthur Oneil left Putnam Investment Management, Llc for Mfs Institutional Advisors Inc. (registered 2026-04-10)
Form ADVobserved 5 days ago
Occurred
May 6, 2022
Advisor changed firm
William Arthur Oneil left Amundi Asset Management Us, Inc. for Putnam Investment Management, Llc (registered 2022-05-25)
Form ADVobserved 5 days ago