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.
Long-equity book
Distinct positions
Filed 2026-10-19
vs 2026-06-30
Portfolio charts
Latest quarter's book, what changed, and how the portfolio has evolved across filings.
Portfolio map
Q3 26Box 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 valueSectors from each company's SIC code; funds and ETFs grouped separately.
Biggest buys and sells
Q2 26 → Q3 26Estimated 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 quartersTotal reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.
Top positions over time
reported valueThe 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.
As of the firm’s regulatory filing dated Mar 30, 2026.
SUITE 1803
BOSTON, MA 02110
| Name | Title / Status | Ownership | Type |
|---|---|---|---|
| MCCARTHY, MICHAEL, STEPHEN Control | CCO/COO/MANAGING MEMBER since Oct 2012 | Less than 5% | Individual |
| MCNAY, JOSEPH, CLAUDIUS Control | CHAIRMAN & MANAGING MEMBER since Oct 2012 | 25–50% | Individual |
| PRIAL, NANCY, BETH Control | CO-CEO & MANAGING MEMBER since Mar 2015 | 10–25% | Individual |
| UEK, ROBERT, JOSEPH Control | CO-CEO & MANAGING MEMBER since Mar 2015 | Less than 5% | Individual |
| BURNT MOUNTAIN INVESTMENTS LLC | NON-MANAGING MEMBER since Feb 2015 | 5–10% | Domestic Entity |
| COURCAP LLC | NON-MANAGING MEMBER since Feb 2015 | 5–10% | Domestic Entity |
| DRAKES MAINE LLC | NON-MANAGING MEMBER since Feb 2015 | 5–10% | Domestic Entity |
| HIPPOGRIFFE INVESTMENT LLC | NON-MANAGING MEMBER since Feb 2015 | 10–25% | Domestic Entity |
| LOCKES INVESTMENT LLC | NON-MANAGING MEMBER since Feb 2015 | 5–10% | Domestic Entity |
| MCMICHAEL, ANNEMARIE, GELATA | RESEARCH ANALYST, NON-MANAGING MEMBER since Feb 2015 | 5–10% | Individual |
| SACKS, SARALYN, NMI | SENIOR 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 more | Individual |
| Giroux, Elizabeth, Ferns Control Indirect owner via LOCKES INVESTMENT LLC | OWNER since Feb 2015 | 75% or more | Individual |
| MCCARTHY, MICHAEL, STEPHEN Control Indirect owner via DRAKES MAINE LLC | OWNER since Feb 2015 | 75% or more | Individual |
| PAGE, WILLIAM, HURD Control Indirect owner via BURNT MOUNTAIN INVESTMENTS LLC | OWNER since Feb 2015 | 75% or more | Individual |
| UEK, ROBERT, JOSEPH Control Indirect owner via HIPPOGRIFFE INVESTMENT LLC | OWNER since Feb 2015 | 75% or more | Individual |
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.
- 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
- 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
- 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
- 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
- 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
- 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%
- ChangedCutler, Stephen, D · title MANAGING PRINCIPAL & PRESIDENT → NON-MANAGING MEMBER & PRESIDENT
- ChangedMCNAY, JOSEPH, CLAUDIUS · title MANAGING PRINCIPAL & CHAIRMAN & CEO → MANAGING MEMBER & CHAIRMAN & CEO
- ChangedMCCARTHY, MICHAEL, STEPHEN · title CCO & DIRECTOR OF OPERATIONS → CCO & CHIEF OPERATING OFFICER
- No longer listedALPHA DYNAMICS LLC · NON MANAGER MEMBER · 10–25% · listed since Oct 2011
- ChangedMCNAY, JOSEPH, CLAUDIUS · ownership 50–75% → 75% or more
- 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)
- 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.
Top Adds (vs prior quarter)
- WATTS WATER TECHNOLOGIES INC$4.2M +216805.8%
- NUVATION BIO INC$3.7M +97.6%
- LANTRONIX INC$2.5M +64.8%
- ENERGY SERVICES OF AMER CORP$2.2M +435.7%
- RISKIFIED LTD$2.0M +52.2%
Top Trims
- LINCOLN EDL SVCS CORP-$10.9M -64.2%
- OUSTER INC-$8.0M -56.3%
- ARTERIS INC-$7.1M -52.9%
- TOWER SEMICONDUCTOR LTD-$6.7M -24.3%
- ARGAN INC-$6.7M -54.1%
New Positions
- ALPHA COGNITION INC$3.8M
- NVIDIA CORPORATION$3.7M
- LGI HOMES INC$3.7M
- INNOVATIVE SOLUTIONS & SUPPORT$3.4M
- FENNEC PHARMACEUTICALS INC$3.4M
Exited Positions
- CREXENDO INC$5.3M
- OCTAVE SPECIALTY GROUP INC$3.4M
- BRC INC$2.9M
- STEREOTAXIS INC$2.6M
- DISNEY WALT CO$2.2M
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 |
| 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 |
SUITE 1803
BOSTON, MA 02110