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Livermore
Livermore
ZHEN

Mackay Shields LLC

SEC CIK
0000061227
Latest filing
Jul 28, 2026

The latest 13F from Mackay Shields LLC covers Q2 2026 (filed Jul 28, 2026): 108 long positions worth $2.99B. The top 10 holdings make up 28.0% of the portfolio, and the largest is Western Digital Corp at 5.1%. Livermore has 23 filings on Form 13F from this institution, going back to Q1 2021.

What changed in Q2 2026

Share counts compared with Q1 2026: how many positions were new, added to, reduced or sold out, and the biggest buys and sells. Dollar amounts are estimated at the quarter-end prices implied by the filing.

Full comparison
New
13
Est. +$385.7M
Added
5
Est. +$37.9M
Reduced
16
Est. −$14.7M
Sold out
16
Est. −$162.3M

Top 5 holdings

Share of this quarter's portfolio value

  1. Western Digital Corp958102AT2
    5.1%$150.8M
  2. GOOGMAlphabet Inc.
    4.1%$122.6MHistory
  3. MKS Inc55306NAB0
    3.6%$107.5M
  4. Lumentum Hldgs Inc55024UAF6
    2.8%$84.1M
  5. Lantheus Hldgs Inc516544AB9
    2.5%$74.0M

Biggest buys

New and added positions, by estimated amount bought

  1. GOOGMAlphabet Inc.
    +$122.6MNewHistory
  2. Merit Med Sys Inc589889AB0
    +$41.1MNew
  3. Revolution Medicines, Inc.76155XAA8
    +$38.1MNew
  4. Jazz Investments I Ltd472145AH4
    +$34.7MNew
  5. Cyberark Software Ltd23248VAD7
    +$31.6MNew

Largest weight increases

New and added positions, by percentage points of the portfolio gained

  1. GOOGMAlphabet Inc.
    +4.11 pp0.0% → 4.1%History
  2. Merit Med Sys Inc589889AB0
    +1.38 pp0.0% → 1.4%
  3. Revolution Medicines, Inc.76155XAA8
    +1.28 pp0.0% → 1.3%
  4. Jazz Investments I Ltd472145AH4
    +1.16 pp0.0% → 1.2%
  5. Cyberark Software Ltd23248VAD7
    +1.06 pp0.0% → 1.1%

Biggest sells

Reduced and sold-out positions, by estimated amount sold

  1. NCL Corp Ltd62886HBD2
    −$38.0MSold out
  2. Seagate HDD Cayman81180WBL4
    −$31.5MSold out
  3. Jazz Investments I Ltd472145AF8
    −$15.9MSold out
  4. Lumentum Hldgs Inc55024UAD1
    −$15.6MSold out
  5. Cheesecake Factory Inc163072AA9
    −$15.2MSold out

Largest weight decreases

Reduced and sold-out positions, by percentage points of the portfolio lost

  1. NCL Corp Ltd62886HBD2
    −1.39 pp1.4% → 0.0%
  2. Seagate HDD Cayman81180WBL4
    −1.16 pp1.2% → 0.0%
  3. Jazz Investments I Ltd472145AF8
    −0.58 pp0.6% → 0.0%
  4. Lumentum Hldgs Inc55024UAD1
    −0.57 pp0.6% → 0.0%
  5. Cheesecake Factory Inc163072AA9
    −0.56 pp0.6% → 0.0%

Metrics

13F metrics for Q2 2026, computed only from the numbers in the filings. Definitions below.

Portfolio value
$2.99B
+$257.5M (+9.4%) vs. prior quarter
Positions
108
−3 vs. prior quarter
Top 10 concentration
28.0%
Top 10 as share of value
Turnover
6.2%
Q2 2026, one quarter
Average holding period
8.0 quarters
Weighted by value

How these are calculated

  • Portfolio value: the market value of all long positions in the 13F, as reported at quarter end, excluding options.
  • Top 10 concentration: the combined value of the 10 largest positions as a share of portfolio value.
  • Turnover: the smaller of this quarter's estimated purchases and estimated sales, divided by the average of this and last quarter's portfolio value. Estimates multiply the change in shares by the quarter-end price implied by the filing (market value divided by shares); new positions use this quarter's value and sold-out positions last quarter's. Only positions reported in shares count, and it is not calculated when the previous quarter was not filed.
  • Average holding period: how many consecutive quarters each current position has been held (including this one; a quarter without the position or without a filing starts the count over), weighted by this quarter's value. Counting starts with the first 13F in Livermore (Q1 2021), so positions held before then are understated.

13F filings by quarter

22 quarters, going back to Q1 2021. Bars show each quarter's 13F portfolio value; quarters without a filing are left blank.

Peak $13.7B (Q1 2021)

Q1 2021: $13.7BQ2 2021: $10.6BQ3 2021: $10.6BQ4 2021: $12.0BQ1 2022: $11.4BQ2 2022: $4.12BQ3 2022: $3.95BQ4 2022: $3.92BQ1 2023: $3.64BQ2 2023: $3.58BQ3 2023: $3.63BQ4 2023: $3.43BQ1 2024: $3.61BQ2 2024: $3.29BQ3 2024: $3.65BQ4 2024: $3.39BQ1 2025: $3.11BQ2 2025: $3.12BQ3 2025: $2.94BQ4 2025: $2.86BQ1 2026: $2.73BQ2 2026: $2.99B
Q1 2021Q2 2026
13F filings of Mackay Shields LLC by quarter
QuarterFiledPositionsValueTop 3 holdingsChangesFiling
Q2 2026Jul 28, 2026108$2.99BWestern Digital CorpGOOGMMKS Incvs. Q1 2026SEC
Q1 2026Apr 27, 2026111$2.73BLumentum Hldgs IncWestern Digital CorpAdvanced Energy Indsvs. Q4 2025SEC
Q4 2025Jan 29, 2026132$2.86BWestern Digital CorpLumentum Hldgs IncAdvanced Energy Indsvs. Q3 2025SEC
Q3 2025Oct 27, 2025136$2.94BSeagate HDD CaymanQXO.PBTetra Tech Incvs. Q2 2025SEC
Q2 2025Jul 24, 2025145$3.12BTetra Tech IncLantheus Hldgs IncPost Hldgs Incvs. Q1 2025SEC
Q1 2025Apr 29, 2025144$3.11BLantheus Hldgs IncNRG Energy, Inc.Post Hldgs Incvs. Q4 2024SEC
Q4 2024Feb 4, 2025147$3.39BTetra Tech IncLantheus Hldgs IncNRG Energy, Inc.vs. Q3 2024SEC
Q3 2024Oct 31, 2024144$3.65BLantheus Hldgs IncTetra Tech IncTransMedics Group, Inc.vs. Q2 2024SEC
Q2 2024Aug 8, 2024139$3.29BTransMedics Group, Inc.Palo Alto Networks IncNICE Ltd.vs. Q1 2024SEC
Q1 2024May 3, 2024140$3.61BGPORNICE Ltd.Pioneer Nat Res Covs. Q4 2023SEC
Q4 2023Feb 2, 2024139$3.43BGPORNICE Ltd.Pioneer Nat Res Covs. Q3 2023SEC
Q3 2023Oct 25, 2023137$3.63BGPORHelix Energy Solutions Grp IEQT Corpvs. Q2 2023SEC
Q2 2023Jul 27, 2023147$3.58BGPORNICE Ltd.EQT Corpvs. Q1 2023SEC
Q1 2023Apr 27, 2023154$3.64BGPORDanaher CorpNICE Ltd.vs. Q4 2022SEC
Q4 2022Jan 31, 2023241$3.92BGPORPioneer Nat Res CoEQT Corpvs. Q3 2022SEC
Q3 2022Nov 2, 2022241$3.95BGPOREQT CorpPioneer Nat Res Covs. Q2 2022SEC
Q2 2022Aug 3, 2022244$4.12BGPORPioneer Nat Res CoEQT Corpvs. Q1 2022SEC
Q1 2022May 13, 2022731$11.4BSPYVanguard S&P 500 ETFAAPLvs. Q4 2021SEC
Q4 2021Feb 4, 2022717$12.0BSPYVanguard S&P 500 ETFAAPLvs. Q3 2021SEC
Q3 2021Jan 18, 2022Amended711$10.6BSPYVanguard S&P 500 ETFAAPLvs. Q2 2021SEC
Q2 2021Aug 13, 2021708$10.6BSPYVanguard S&P 500 ETFAAPLvs. Q1 2021SEC
Q1 2021May 14, 20211,497$13.7BVanguard S&P 500 ETFSPYAAPL–SEC

13D and 13G filings

Companies where Mackay Shields LLC reports owning 5% or more on Schedule 13D or 13G, and its latest filings.

Current stakes of 5% or more

1 company, largest stake first.

Companies where Mackay Shields LLC owns 5% or more
CompanyLatest formStakeChangeFirst filedLatest filingFiling
NINENine Energy Service, Inc.13G11.91%1.66M shares0.00 ppfrom 11.91%Mar 31, 20262 filingsMar 31, 2026SEC

Latest filings

27 filings on file made by Mackay Shields LLC or listing it as a reporting person; the latest 20 are shown.

Schedule 13D and 13G filings by Mackay Shields LLC
CompanyFiled (ET)FormStakeChangeEvent dateFiling
NINENine Energy Service, Inc.Mar 31, 20263:20 PM ET13G11.91%1.66M shares0.00 ppfrom 11.91%Mar 5, 2026SEC
NINENine Energy Service, Inc.Mar 31, 20261:36 PM ET13G11.91%1.66M sharesNewMar 5, 2026SEC
FETForum Energy Technologies, Inc.Sep 18, 202512:00 PM ET13G/A2.05%244.2K shares−5.37 ppfrom 7.42%Below 5%Sep 16, 2025SEC
FETForum Energy Technologies, Inc.Jan 22, 202510:11 AM ET13G/A7.42%911.3K shares–Dec 31, 2024SEC
GPORGulfport Energy CorpApr 12, 202413G/AOld format–––SEC
GPORGulfport Energy CorpJan 11, 202413G/AOld format–––SEC
FETForum Energy Technologies, Inc.Jan 11, 202413G/AOld format–––SEC
FETForum Energy Technologies, Inc.Jan 11, 202413G/AOld format–––SEC
GPORGulfport Energy CorpJan 11, 202413G/AOld format–––SEC
MQTBlackRock Muniyield Quality Fund II, Inc.Apr 13, 202313G/AOld format–––SEC
FETForum Energy Technologies, Inc.Jan 17, 202313G/AOld format–––SEC
FETForum Energy Technologies, Inc.Jan 13, 202313GOld format–New–SEC
GPORGulfport Energy CorpJan 6, 202313G/AOld format–––SEC
MQTBlackRock Muniyield Quality Fund II, Inc.Jan 6, 202313G/AOld format–––SEC
VFLabrdn National Municipal Income FundJan 6, 202313G/AOld format–––SEC
MAVPioneer Municipal High Income Advantage Fund, Inc.Jan 13, 202213G/AOld format–––SEC
MQTBlackRock Muniyield Quality Fund II, Inc.Jan 12, 202213G/AOld format–––SEC
VFLabrdn National Municipal Income FundJan 12, 202213G/AOld format–––SEC
MUIBlackRock Municipal Credit Alpha Portfolio, Inc.Oct 28, 202113G/AOld format–––SEC
MUJBlackRock Muniholdings New Jersey Quality Fund, Inc.Oct 28, 202113G/AOld format–––SEC