ESSEX INVESTMENT MANAGEMENT CO LLC — 13F Holdings & Portfolio

CIK 201772 · latest 13F-HR filed 2026-10-19

ESSEX INVESTMENT MANAGEMENT CO LLC manages $674.7M in 13F-reported U.S. long-equity assets across 301 reported positions as of its 2026-09-30 13F-HR filing. Its largest disclosed positions are TSEM (3.08%), KNSA (2.23%), LGND (1.80%). Quarter over quarter (versus its 2026-06-30 filing) the fund opened 21 new positions and exited 26; 76 existing positions rose in reported value and 154 fell.

AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.

Loading holdings…
AUM
$674.7M

Long-equity book

Holdings
301

Distinct positions

Period
2026-09-30

Filed 2026-10-19

Q/Q Activity
+21 / −26 / ↑76 / ↓154

vs 2026-06-30

Portfolio charts

Latest quarter's book, what changed, and how the portfolio has evolved across filings.

Portfolio map

Q3 26

Box size = position value; colour = change in share count vs the prior quarter (green added, red trimmed, blue new). Rows split across managers or share classes are combined. Click a box for the stock.

Sector mix

% of 13F value

Sectors from each company's SIC code; funds and ETFs grouped separately.

Biggest buys and sells

Q2 26 → Q3 26

Estimated from the change in shares held × the quarter-end price, so price moves alone don't count as buying. New and exited positions are included.

13F assets and positions

5 quarters

Total reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.

Top positions over time

reported value

The eight largest current positions, valued at each quarter end.

Concentration

top 10 = 17.2%

Cumulative share of the portfolio held in the largest N positions.

Firm Profile & Key People

As of the firm’s regulatory filing dated Mar 30, 2026.

Assets Under Management
$712.7M
Discretionary
$712.7M
Employees
13
Accounts
117
Address
125 HIGH STREET
SUITE 1803
BOSTON, MA 02110
Phone
(617) 342-3200
Name Title / Status Ownership Type
MCCARTHY, MICHAEL, STEPHEN ControlCCO/COO/MANAGING MEMBER
since Oct 2012
Less than 5%Individual
MCNAY, JOSEPH, CLAUDIUS ControlCHAIRMAN & MANAGING MEMBER
since Oct 2012
25–50%Individual
PRIAL, NANCY, BETH ControlCO-CEO & MANAGING MEMBER
since Mar 2015
10–25%Individual
UEK, ROBERT, JOSEPH ControlCO-CEO & MANAGING MEMBER
since Mar 2015
Less than 5%Individual
BURNT MOUNTAIN INVESTMENTS LLCNON-MANAGING MEMBER
since Feb 2015
5–10%Domestic Entity
COURCAP LLCNON-MANAGING MEMBER
since Feb 2015
5–10%Domestic Entity
DRAKES MAINE LLCNON-MANAGING MEMBER
since Feb 2015
5–10%Domestic Entity
HIPPOGRIFFE INVESTMENT LLCNON-MANAGING MEMBER
since Feb 2015
10–25%Domestic Entity
LOCKES INVESTMENT LLCNON-MANAGING MEMBER
since Feb 2015
5–10%Domestic Entity
MCMICHAEL, ANNEMARIE, GELATARESEARCH ANALYST, NON-MANAGING MEMBER
since Feb 2015
5–10%Individual
SACKS, SARALYN, NMISENIOR PORTFOLIO MANAGER & NON-MANAGING MEMBER
since Mar 2015
5–10%Individual
COURNAN, MARTIN, PIERCE Control
Indirect owner via COURCAP LLC
OWNER
since Feb 2015
75% or moreIndividual
Giroux, Elizabeth, Ferns Control
Indirect owner via LOCKES INVESTMENT LLC
OWNER
since Feb 2015
75% or moreIndividual
MCCARTHY, MICHAEL, STEPHEN Control
Indirect owner via DRAKES MAINE LLC
OWNER
since Feb 2015
75% or moreIndividual
PAGE, WILLIAM, HURD Control
Indirect owner via BURNT MOUNTAIN INVESTMENTS LLC
OWNER
since Feb 2015
75% or moreIndividual
UEK, ROBERT, JOSEPH Control
Indirect owner via HIPPOGRIFFE INVESTMENT LLC
OWNER
since Feb 2015
75% or moreIndividual
Ownership & leadership changes · 10 filings with changes since Mar 30, 2012

From the firm’s regulatory filings, newest first. Dates are filing dates: a filing that no longer lists someone does not say when they left.

Mar 31, 2023 filing
  • No longer listedCOURNAN, MARTIN, PIERCE · SENIOR TRADER & NON-MANAGING MEMBER · Less than 5% · listed since Apr 2002
  • No longer listedGiroux, Elizabeth, Ferns · HEAD TRADER & NON-MANAGING MEMBER · Less than 5% · listed since Apr 2002
  • AddedBURNT MOUNTAIN INVESTMENTS LLC · NON-MANAGING MEMBER · 5–10%
  • AddedMCMICHAEL, ANNEMARIE, GELATA · RESEARCH ANALYST, NON-MANAGING MEMBER · 5–10%
  • AddedPAGE, WILLIAM, HURD · OWNER · 75% or more · indirect via BURNT MOUNTAIN INVESTMENTS LLC · control person
Mar 31, 2021 filing
  • No longer listed6 PART FIVE LLC · NON-MANAGING MEMBER · 5–10% · listed since Feb 2015
  • No longer listedCutler, Stephen, D · PRESIDENT AND MANAGING MEMBER · Less than 5% · control person · listed since Mar 1998
  • No longer listedFORSE, ALEXANDER, ARMOUR · SENIOR PORTFOLIO MANAGER & NON-MANAGING MEMBER · Less than 5% · listed since May 2018
  • No longer listedFORSE, ALEXANDER, ARMOUR · OWNER · 75% or more · indirect via 6 PART FIVE LLC · control person · listed since Feb 2015
Mar 15, 2019 filing
  • No longer listedHIPPOGRIFFE INVESTMENTS LLC · NON-MANAGING MEMBER · 10–25% · listed since Feb 2015
  • No longer listedUEK, ROBERT, JOSEPH · MANAGING MEMBER OF HIPPOGRAFFE INVESTMENTS LLC · 75% or more · indirect via HIPPOGRAFFE INVESTMENTS LLC · control person · listed since Feb 2015
  • Added6 PART FIVE LLC · NON-MANAGING MEMBER · 5–10%
  • AddedCOURCAP LLC · NON-MANAGING MEMBER · 5–10%
  • AddedCOURNAN, MARTIN, PIERCE · OWNER · 75% or more · indirect via COURCAP LLC · control person
  • AddedCOURNAN, MARTIN, PIERCE · SENIOR TRADER & NON-MANAGING MEMBER · Less than 5%
  • AddedDRAKES MAINE LLC · NON-MANAGING MEMBER · 5–10%
  • AddedFORSE, ALEXANDER, ARMOUR · SENIOR PORTFOLIO MANAGER & NON-MANAGING MEMBER · Less than 5%
  • AddedFORSE, ALEXANDER, ARMOUR · OWNER · 75% or more · indirect via 6 PART FIVE LLC · control person
  • AddedGiroux, Elizabeth, Ferns · OWNER · 75% or more · indirect via LOCKES INVESTMENT LLC · control person
  • AddedGiroux, Elizabeth, Ferns · HEAD TRADER & NON-MANAGING MEMBER · Less than 5%
  • AddedHIPPOGRIFFE INVESTMENT LLC · NON-MANAGING MEMBER · 10–25%
  • AddedLOCKES INVESTMENT LLC · NON-MANAGING MEMBER · 5–10%
  • AddedMCCARTHY, MICHAEL, STEPHEN · OWNER · 75% or more · indirect via DRAKES MAINE LLC · control person
  • AddedUEK, ROBERT, JOSEPH · OWNER · 75% or more · indirect via HIPPOGRIFFE INVESTMENT LLC · control person
  • ChangedCutler, Stephen, D · title PRESIDENT AND MANAGER → PRESIDENT AND MANAGING MEMBER
  • ChangedMCCARTHY, MICHAEL, STEPHEN · title CCO/COO/MANAGER → CCO/COO/MANAGING MEMBER
  • ChangedMCNAY, JOSEPH, CLAUDIUS · title MANAGING MEMBER & CHAIRMAN → CHAIRMAN & MANAGING MEMBER; ownership 50–75% → 25–50%
  • ChangedPRIAL, NANCY, BETH · title MANAGING MEMBER & CO-CEO → CO-CEO & MANAGING MEMBER
  • ChangedSACKS, SARALYN, NMI · title NON-MANAGING MEMBER → SENIOR PORTFOLIO MANAGER & NON-MANAGING MEMBER
  • ChangedUEK, ROBERT, JOSEPH · title CO-CEO AND MANAGER → CO-CEO & MANAGING MEMBER
Mar 29, 2017 filing
  • No longer listedCORTEZ, LUIS, RAFAEL · MANAGING MEMBER OF LRC INVESTMENTS LLC · 75% or more · indirect via LRC INVESTMENTS LLC · control person · listed since Mar 2015
  • No longer listedLRC INVESTMENTS LLC · NON-MANAGING MEMBER · 5–10% · listed since Feb 2012
Mar 29, 2016 filing
  • ChangedCutler, Stephen, D · title PRESIDENT → PRESIDENT AND MANAGER
  • ChangedHIPPOGRIFFE INVESTMENTS LLC · ownership 5–10% → 10–25%
  • ChangedMCCARTHY, MICHAEL, STEPHEN · title CCO & CHIEF OPERATING OFFICER → CCO/COO/MANAGER
  • ChangedPRIAL, NANCY, BETH · title NON-MANAGING MEMBER & CO-CEO → MANAGING MEMBER & CO-CEO
  • ChangedUEK, ROBERT, JOSEPH · title CO-CEO → CO-CEO AND MANAGER
Mar 26, 2015 filing
  • AddedCORTEZ, LUIS, RAFAEL · MANAGING MEMBER OF LRC INVESTMENTS LLC · 75% or more · indirect via LRC INVESTMENTS LLC · control person
  • AddedHIPPOGRIFFE INVESTMENTS LLC · NON-MANAGING MEMBER · 5–10%
  • AddedLRC INVESTMENTS LLC · NON-MANAGING MEMBER · 5–10%
  • AddedPRIAL, NANCY, BETH · NON-MANAGING MEMBER & CO-CEO · 10–25% · control person
  • AddedSACKS, SARALYN, NMI · NON-MANAGING MEMBER · 5–10%
  • AddedUEK, ROBERT, JOSEPH · CO-CEO · Less than 5% · control person
  • AddedUEK, ROBERT, JOSEPH · MANAGING MEMBER OF HIPPOGRAFFE INVESTMENTS LLC · 75% or more · indirect via HIPPOGRAFFE INVESTMENTS LLC · control person
  • ChangedCutler, Stephen, D · title NON-MANAGING MEMBER & PRESIDENT → PRESIDENT
  • ChangedMCCARTHY, MICHAEL, STEPHEN · now a control person
  • ChangedMCNAY, JOSEPH, CLAUDIUS · title MANAGING MEMBER & CHAIRMAN & CEO → MANAGING MEMBER & CHAIRMAN; ownership 75% or more → 50–75%
May 27, 2014 filing
  • ChangedCutler, Stephen, D · title MANAGING PRINCIPAL & PRESIDENT → NON-MANAGING MEMBER & PRESIDENT
  • ChangedMCNAY, JOSEPH, CLAUDIUS · title MANAGING PRINCIPAL & CHAIRMAN & CEO → MANAGING MEMBER & CHAIRMAN & CEO
Mar 24, 2014 filing
  • ChangedMCCARTHY, MICHAEL, STEPHEN · title CCO & DIRECTOR OF OPERATIONS → CCO & CHIEF OPERATING OFFICER
Dec 11, 2013 filing
  • No longer listedALPHA DYNAMICS LLC · NON MANAGER MEMBER · 10–25% · listed since Oct 2011
  • ChangedMCNAY, JOSEPH, CLAUDIUS · ownership 50–75% → 75% or more
Nov 5, 2012 filing
  • No longer listedAFFILIATED MANAGERS GROUP, INC. · MANAGER MEMBER · 75% or more · indirect via AMG BOSTON HOLDINGS, LLC · control person · listed since Dec 2010
  • No longer listedAMG BOSTON HOLDINGS, LLC · MANAGING MEMBER · 50–75% · control person · listed since Dec 2010
  • No longer listedCOULTER, DEBORAH, ANN · SENIOR PRINCIPAL & CHIEF FINANCIAL OFFICER · Less than 5% · listed since Jan 2007
  • No longer listedMCCONNELL, CHRISTOPHER, PAUL · CEO/MANAGING PRINCIPAL/CHIEF COMPLIANCE OFFICER · Less than 5% · control person · listed since Mar 1998
  • AddedMCCARTHY, MICHAEL, STEPHEN · CCO & DIRECTOR OF OPERATIONS · Less than 5%
  • ChangedMCNAY, JOSEPH, CLAUDIUS · title MANAGING PRINCIPAL & CHAIRMAN → MANAGING PRINCIPAL & CHAIRMAN & CEO; ownership 5–10% → 50–75%
Older changes (1 more filing)
Mar 30, 2012 filing (earliest on record)
  • ListedAFFILIATED MANAGERS GROUP, INC. · MANAGER MEMBER · 75% or more · indirect via AMG BOSTON HOLDINGS, LLC · control person
  • ListedALPHA DYNAMICS LLC · NON MANAGER MEMBER · 10–25%
  • ListedAMG BOSTON HOLDINGS, LLC · MANAGING MEMBER · 50–75% · control person
  • ListedCOULTER, DEBORAH, ANN · SENIOR PRINCIPAL & CHIEF FINANCIAL OFFICER · Less than 5%
  • ListedCutler, Stephen, D · MANAGING PRINCIPAL & PRESIDENT · Less than 5% · control person
  • ListedMCCONNELL, CHRISTOPHER, PAUL · CEO/MANAGING PRINCIPAL/CHIEF COMPLIANCE OFFICER · Less than 5% · control person
  • ListedMCNAY, JOSEPH, CLAUDIUS · MANAGING PRINCIPAL & CHAIRMAN · 5–10% · control person

Quarter-over-quarter changes

Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.

ESSEX INVESTMENT MANAGEMENT CO LLC Holdings (2026-09-30)

Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).

# Issuer Symbol CUSIP Value Weight Shares Type
1 TOWER SEMICONDUCTOR LTD TSEM M87915274 $20.8M 3.08% 91,519 SH
2 KINIKSA PHARMACEUTICALS INTL P KNSA G52694109 $15.1M 2.23% 202,021 SH
3 LIGAND PHARMACEUTICALS INC LGND 53220K504 $12.2M 1.80% 38,917 SH
4 ADAPTIVE BIOTECHNOLOGIES CORP ADPT 00650F109 $11.6M 1.72% 401,735 SH
5 APPLE INC AAPL 037833100 $10.4M 1.53% 31,084 SH
6 CECO ENVIRONMENTAL CORP CECO 125141101 $10.1M 1.50% 145,717 SH
7 HCI GROUP INC HCI 40416E103 $9.4M 1.40% 54,282 SH
8 LEONARDO DRS INC DRS 52661A108 $8.9M 1.32% 242,479 SH
9 MIRUM PHARMACEUTICALS INC MIRM 604749101 $8.7M 1.29% 101,716 SH
10 COHU INC COHU 192576106 $8.7M 1.28% 127,180 SH
11 AVEPOINT INC AVPT 053604104 $7.8M 1.15% 551,987 SH
12 STERLING INFRASTRUCTURE INC STRL 859241101 $7.6M 1.13% 15,536 SH
13 TRAVERE THERAPEUTICS INC TVTX 89422G107 $7.6M 1.13% 129,493 SH
14 BRAINSWAY LTD BWAY 10501L106 $7.6M 1.12% 574,818 SH
15 GE VERNOVA INC GEV 36828A101 $7.6M 1.12% 7,978 SH
16 NUVATION BIO INC NUVB 67080N101 $7.5M 1.12% 1,344,871 SH
17 WERNER ENTERPRISES INC WERN 950755108 $7.5M 1.11% 220,515 SH
18 MICROSOFT CORP MSFT 594918104 $7.4M 1.10% 14,469 SH
19 FREQUENCY ELECTRS INC FEIM 358010106 $7.3M 1.08% 86,267 SH
20 BIODESIX INC BDSX 09075X207 $7.0M 1.04% 234,542 SH
21 AGNICO EAGLE MINES LTD AEM 008474108 $6.8M 1.01% 37,195 SH
22 NOVOCURE LTD NVCR G6674U108 $6.8M 1.00% 424,133 SH
23 XERIS BIOPHARMA HOLDINGS INC XERS 98422E103 $6.6M 0.98% 693,260 SH
24 SEMTECH CORP SMTC 816850101 $6.6M 0.98% 37,026 SH
25 MARVELL TECHNOLOGY INC MRVL 573874104 $6.6M 0.97% 24,845 SH
26 GRAHAM CORP GHM 384556106 $6.5M 0.96% 75,219 SH
27 AMAZON COM INC AMZN 023135106 $6.4M 0.96% 25,879 SH
28 LANTRONIX INC LTRX 516548203 $6.4M 0.95% 889,983 SH
29 OCEANEERING INTL INC OII 675232102 $6.4M 0.95% 146,483 SH
30 GOLDMAN SACHS GROUP INC GS 38141G104 $6.4M 0.94% 7,069 SH
31 ARTERIS INC AIP 04302A104 $6.4M 0.94% 268,987 SH
32 KRATOS DEFENSE & SEC SOLUTIONS KTOS 50077B207 $6.3M 0.94% 148,246 SH
33 OUSTER INC OUST 68989M202 $6.2M 0.91% 152,925 SH
34 ASML HLDG NV ASML N07059210 $6.1M 0.91% 3,394 SH
35 LINCOLN EDL SVCS CORP LINC 533535100 $6.1M 0.90% 278,205 SH
36 AMERICAN SUPERCONDUCTOR CORP AMSC 030111207 $6.0M 0.89% 205,382 SH
37 BLUELINX HLDGS INC BXC 09624H208 $6.0M 0.89% 83,955 SH
38 LSI INDS INC OHIO LYTS 50216C108 $6.0M 0.88% 287,681 SH
39 RISKIFIED LTD RSKD M8216R109 $5.9M 0.87% 745,621 SH
40 PRECIGEN INC PGEN 74017N105 $5.9M 0.87% 683,419 SH
41 ARGAN INC AGX 04010E109 $5.7M 0.84% 15,016 SH
42 908 DEVICES INC MASS 65443P102 $5.6M 0.83% 455,706 SH
43 XOMETRY INC XMTR 98423F109 $5.6M 0.83% 54,162 SH
44 SOPHIA GENETICS SA SOPH H82027105 $5.4M 0.80% 643,129 SH
45 AMBARELLA INC AMBA G037AX101 $5.4M 0.80% 77,245 SH
46 WILLDAN GROUP INC WLDN 96924N100 $5.4M 0.79% 72,557 SH
47 PATRICK INDS INC PATK 703343103 $5.4M 0.79% 78,964 SH
48 GENTHERM INC THRM 37253A103 $5.3M 0.78% 158,243 SH
49 MISTRAS GROUP INC MG 60649T107 $5.2M 0.78% 249,209 SH
50 FORUM ENERGY TECHNOLOGIES INC FET 34984V209 $5.2M 0.77% 64,563 SH
Filing History
Period Filed AUM Holdings Accession
2026-09-30 2026-10-19 $674.7M 301 0000201772-26-000007
2026-06-30 2026-08-06 $763.4M 306 0000201772-26-000005
2026-03-31 2026-05-11 $631.7M 305 0000201772-26-000004
2025-12-31 2026-02-13 $655.9M 306 0000201772-26-000001
2025-09-30 2025-11-06 $653.4M 299 0000201772-25-000008
Filer Information
Address
125 HIGH STREET
SUITE 1803
BOSTON, MA 02110
Phone
(617) 482-4870
Filing Manager
ESSEX INVESTMENT MANAGEMENT CO LLC
BOSTON, MA
Signatory
David Rozenson
Attorney-in-Fact