Filer Snapshot

MACKAY SHIELDS LLC

CIK 0000061227. SEC filing timeline plus parsed ownership intelligence from 13F, 13D/G, and Forms 3/4/5 where available.

Entity type

Company

Total filings

378

Latest filing

27 Apr 2026

Industry

n/a

Filing-backed research brief

Start with the SEC data that changes for this CIK

Latest signal: 13F-HR for Q1 2026. Each card links back to the PortfolioSavvy page where the filing evidence is closest.

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Largest parsed holding

Lumentum Hldgs Inc

$143.55M reported value

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13D/G large stake

Nine Energy Service, Inc.

05 Mar 2026 · 12% ownership

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Source: SEC Form 13F

13F-HR filed on 27 Apr 2026 for CIK 0000061227.

View Source Filing
Identity
Business address
299 Park Avenue, 32 Nd Floor, New York, NY, 10171
SEC ownership signals
Parsed ownership coverage

13F reported value

$2.73B

Latest parsed Form 13F reported market value.

Largest 13F symbols

LUMENTUM HLDGS INC, WESTERN DIGITAL CORP, ADVANCED ENERGY INDS, MIRUM PHARMACEUTICALS INC

Largest symbols in the latest parsed Form 13F holdings.

Schedule 13G stakes
FET Nine Energy Service, Inc.
Largest 13F holdings
LUMENTUM HLDGS INC WESTERN DIGITAL CORP ADVANCED ENERGY INDS MIRUM PHARMACEUTICALS INC QXOPRB LANTHEUS HLDGS INC MKS INC. CABLE ONE INC
+12 moreTETRA TECH INC NEW UBER TECHNOLOGIES INC BAPRA ON SEMICONDUCTOR CORP PG&E CORP POST HLDGS INC INTEGER HLDGS CORP APOPRA LIBERTY MEDIA CORP DEL AKAMAI TECHNOLOGIES INC HPEPRC SNOWFLAKE INC
SEC record
State of incorporation
DE
Fiscal year end
31 December
Former names
MACKAY SHIELDS FINANCIAL CORP (to 07 Feb 2001)

Filer intelligence

What SEC filings say about MACKAY SHIELDS LLC

A compact read of parsed XML filings. 13F, 13D/G, and Forms 3/4/5 are shown separately because they answer different ownership questions.

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Quick read

  • Latest parsed 13F shows $2.73B across 111 reported holdings for Q1 2026.
  • Largest parsed 13F holding: LUMENTUM HLDGS INC at $143.55M.
  • 2 recent 13D/G stake rows found; top row is Nine Energy Service, Inc. at 12% ownership.
  • Forms 3/4/5 show insider context for MMIOX.

SEC source mix

Counts show available parsed rows, not one combined ownership total.

XML parsed
13F portfolio 111 rows

Quarterly institutional portfolio holdings.

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13D/G stakes 2 rows

Beneficial ownership and large-stake disclosures.

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Forms 3/4/5 2 rows

Officer, director, and 10% owner holdings or transactions.

Open

Top parsed 13F holdings

Visual share of the latest parsed 13F portfolio. Values are reported market value, not a recommendation.

Q1 2026 - 27 Apr 2026

Top 5 concentration

18%

Share of latest parsed 13F value represented by the visible holdings below.

Top 5 reported value

$483.98M

Compared with $2.73B total 13F value.

Top 5 net change

-$61.29M

Position-value change inside the visible top holdings only.

13F concentration map

A simple visual split of the latest parsed 13F portfolio.

Largest add: Integer Hldgs Corp · Largest trim: Seagate Hdd Cayman

Lumentum Hldgs Inc Western Digital Corp Advanced Energy Inds Mirum Pharmaceuticals Inc QXOPRB Other holdings

13D/G large-stake context

Nine Energy Service, Inc.

05 Mar 2026 · Common Stock

12%
Issuer page 13D/G history

FET

16 Sep 2025 · Common Stock

2%
Issuer page 13D/G history

Forms 3/4/5 insider context

MMIOX

25 Mar 2024

Issuer page Owner page

RMMZ

10 Feb 2022

Issuer page Owner page

Latest update

What changed recently for MACKAY SHIELDS LLC

New filing available

Latest 13F period: Q1 2026. Open the source-backed page to inspect the fresh filing or facts context.

Update date

27 Apr 2026

Page type

Filer profile

Latest period

Q1 2026

Institutional portfolio context was refreshed from a 13F filing filed on 27 Apr 2026.

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Benchmark Context

Benchmark context for this company

MACKAY SHIELDS LLC has a source-backed company facts view where you can compare the latest reported metrics with its own recent history and with peer rankings for the same metric.

Compared with

Start on the facts page for period-to-period context, then open a metric ranking when you want to compare the same reported fact across other SEC-reporting companies.

Why this is notable

Latest 13F period: Q1 2026. That gives you a fresh baseline before you compare this company with peers.

  • Peer comparisons stay conservative: same metric, compatible units, latest valid company row only.
  • Open the facts page first if you want the cleanest path to verification.

Benchmark context is only shown where the app has enough comparable SEC-backed data to keep the interpretation honest.

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SEC filing record

CIK 0000061227 filing coverage

Start with this filing record, then use the linked ownership pages when parsed 13F, 13D/G, Forms 3/4/5, or facts data exists for this CIK.

SEC filings
378
First seen
10 Feb 1995
Latest filing
27 Apr 2026
Entity
Company

Observed form types

13F-HR SCHEDULE 13G SCHEDULE 13G/A N-PX SC 13G/A 3 SC 13G 13F-HR/A 144 SC 13D +4 more

Primary evidence

Open SEC filing index MACKAY SHIELDS LLC SEC filings MACKAY SHIELDS LLC 13F portfolio MACKAY SHIELDS LLC 13D/G history MACKAY SHIELDS LLC owner filings

Latest Filings

Showing the latest 12 of 151 SEC filings for MACKAY SHIELDS LLC.

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13F-HR File 028-00046

13F-HR filing

Filing date
27 Apr 2026
Reporting date
31 Mar 2026
SEC evidence
Open document Open filing
Next action
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SCHEDULE 13G

SCHEDULE 13G filing

Filing date
31 Mar 2026
Reporting date
Not listed
SEC evidence
Open document Open filing
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SCHEDULE 13G

SCHEDULE 13G filing

Filing date
31 Mar 2026
Reporting date
Not listed
SEC evidence
Open document Open filing
Next action
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13F-HR File 028-00046

13F-HR filing

Filing date
29 Jan 2026
Reporting date
31 Dec 2025
SEC evidence
Open document Open filing
Next action
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13F-HR File 028-00046

13F-HR filing

Filing date
27 Oct 2025
Reporting date
30 Sep 2025
SEC evidence
Open document Open filing
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SCHEDULE 13G/A

SCHEDULE 13G/A filing

Filing date
18 Sep 2025
Reporting date
Not listed
SEC evidence
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N-PX File 028-00046

N-PX filing

Filing date
28 Aug 2025
Reporting date
30 Jun 2025
SEC evidence
Open document Open filing
Next action
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13F-HR File 028-00046

13F-HR filing

Filing date
24 Jul 2025
Reporting date
30 Jun 2025
SEC evidence
Open document Open filing
Next action
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13F-HR File 028-00046

13F-HR filing

Filing date
29 Apr 2025
Reporting date
31 Mar 2025
SEC evidence
Open document Open filing
Next action
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13F-HR File 028-00046

13F-HR filing

Filing date
04 Feb 2025
Reporting date
31 Dec 2024
SEC evidence
Open document Open filing
Next action
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SCHEDULE 13G/A

SCHEDULE 13G/A filing

Filing date
22 Jan 2025
Reporting date
Not listed
SEC evidence
Open document Open filing
Next action
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13F-HR File 028-00046

13F-HR filing

Filing date
31 Oct 2024
Reporting date
30 Sep 2024
SEC evidence
Open document Open filing
Next action
Verify source filing
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