Q3 2026 13F · SEC CIK 201772

Essex Investment Management Co LLC

Asset managerFiled 2026-10-19 for Q3 2026. Open the filing ↗ · All SEC filings ↗

Reported 13F value: $674.7M
Reported positions: 301
Top holdings a year, 3 yrs: +43.4%
Assets under management: $712.7M

Essex Investment Management Co LLC is an asset manager that reported 301 positions worth $674.7M in its Q3 2026 13F, filed 2026-10-19. Its largest holdings were Tower Semiconductor Ltd (TSEM, 3.1%), Kiniksa Pharmaceuticals Intl (KNSA, 2.2%), Ligand Pharmaceuticals Inc (LGND, 1.8%). A portfolio copying its top holdings returned 43.4% a year over the last 3 years, against 20.4% for the S&P 500.

Essex Investment Management Co LLC holdings largest 50 of 301 positions.

Weights are shares of the filer's total reported 13F value, compared with Q2 2026. Share changes may reflect splits; weight changes also reflect price moves. A 13F shows long US-listed positions only, up to 135 days after the fact.

Essex Investment Management Co LLC 13F holdings
Stock	% of 13F value	Q2 2026	Shares	Share change	Reported value
TSEMTower Semiconductor Ltd	3.1%	3.6%	91,519	-13.3%	$20.8M
KNSAKiniksa Pharmaceuticals Intl	2.2%	2.0%	202,021	-16.3%	$15.1M
LGNDLigand Pharmaceuticals Inc	1.8%	1.8%	38,917	-10.7%	$12.2M
ADPTAdaptive Biotechnologies Corp	1.7%	1.3%	401,735	-15.0%	$11.6M
AAPLApple Inc	1.5%	1.2%	31,084	-4.1%	$10.4M
CECOCeco Environmental Corp	1.5%	1.8%	145,717	-3.1%	$10.1M
HCIHci Group Inc	1.4%	1.3%	54,282	-3.5%	$9.4M
DRSLeonardo Drs Inc	1.3%	1.4%	242,479	-3.1%	$8.9M
MIRMMirum Pharmaceuticals Inc	1.3%	1.6%	101,716	-3.7%	$8.7M
COHUCohu Inc	1.3%	1.3%	127,180	-3.0%	$8.7M
AVPTAvepoint Inc	1.2%	0.8%	551,987	-3.4%	$7.8M
STRLSterling Infrastructure Inc	1.1%	1.8%	15,536	-3.8%	$7.6M
TVTXTravere Therapeutics Inc	1.1%	1.0%	129,493	-3.3%	$7.6M
BWAYBrainsway Ltd	1.1%	1.2%	574,818	-3.0%	$7.6M
GEVGe Vernova Inc	1.1%	1.3%	7,978	-3.7%	$7.6M
NUVBNuvation Bio Inc	1.1%	—	1,344,871	—	$7.5M
WERNWerner Enterprises Inc	1.1%	1.3%	220,515	-4.8%	$7.5M
MSFTMicrosoft Corp	1.1%	0.8%	14,469	-7.9%	$7.4M
FEIMFrequency Electrs Inc	1.1%	0.8%	86,267	-3.1%	$7.3M
BDSXBiodesix Inc	1.0%	0.7%	234,542	-3.0%	$7.0M
AEMAgnico Eagle Mines Ltd	1.0%	0.8%	37,195	-3.3%	$6.8M
NVCRNovocure Ltd	1.0%	0.9%	424,133	-3.5%	$6.8M
XERSXeris Biopharma Holdings Inc	1.0%	0.7%	693,260	-3.1%	$6.6M
SMTCSemtech Corp	1.0%	0.8%	37,026	-3.1%	$6.6M
MRVLMarvell Technology Inc	1.0%	1.0%	24,845	-4.1%	$6.6M
GHMGraham Corp	1.0%	1.5%	75,219	-19.5%	$6.5M
AMZNAmazon Com Inc	1.0%	0.8%	25,879	-4.4%	$6.4M
LTRXLantronix Inc	1.0%	—	889,983	—	$6.4M
OIIOceaneering Intl Inc	0.9%	0.8%	146,483	-3.3%	$6.4M
GSGoldman Sachs Group Inc	0.9%	1.0%	7,069	-5.9%	$6.4M
AIPArteris Inc	0.9%	1.8%	268,987	-3.1%	$6.4M
KTOSKratos Defense & Security Solutions Inc	0.9%	1.0%	148,246	-3.5%	$6.3M
OUSTOuster Inc	0.9%	1.9%	152,925	-32.3%	$6.2M
ASMLAsml Hldg NV	0.9%	0.9%	3,394	-4.1%	$6.1M
LINCLincoln Educational Srvcs	0.9%	2.2%	278,205	-18.3%	$6.1M
AMSCAmerican Superconductor Corp	0.9%	1.2%	205,382	-7.5%	$6.0M
BXCBluelinx Hldgs Inc	0.9%	0.7%	83,955	-3.0%	$6.0M
LYTSLsi Inds Inc Ohio	0.9%	1.0%	287,681	-2.8%	$6.0M
RSKDRiskified Ltd	0.9%	—	745,621	—	$5.9M
PGENPrecigen Inc	0.9%	—	683,419	—	$5.9M
AGXArgan Inc	0.8%	1.6%	15,016	-2.9%	$5.7M
MASS908 Devices Inc	0.8%	—	455,706	—	$5.6M
XMTRXometry, Inc.	0.8%	0.7%	54,162	-3.1%	$5.6M
SOPHSophia Genetics SA	0.8%	—	643,129	—	$5.4M
AMBAAmbarella Inc	0.8%	0.9%	77,245	-3.4%	$5.4M
WLDNWilldan Group Inc	0.8%	0.8%	72,557	-3.1%	$5.4M
PATKPatrick Inds Inc	0.8%	1.0%	78,964	-4.8%	$5.4M
THRMGentherm Inc	0.8%	—	158,243	—	$5.3M
MGMistras Group Inc	0.8%	—	249,209	—	$5.2M
FETForum Energy Technologies Inc	0.8%	—	64,563	—	$5.2M

What Essex Investment Management Co LLC bought and sold in Q3 2026, against Q2 2026.

New positions

Q2 2026's filing was too long to tell new positions apart.

Added to

No position grew by more than 5%.

Reduced

OUST Ouster Inc-32.3% shares
GHM Graham Corp-19.5% shares
LINC Lincoln Educational Srvcs-18.3% shares
KNSA Kiniksa Pharmaceuticals Intl-16.3% shares
ADPT Adaptive Biotechnologies Corp-15.0% shares
TSEM Tower Semiconductor Ltd-13.3% shares
LGND Ligand Pharmaceuticals Inc-10.7% shares
MSFT Microsoft Corp-7.9% shares

Left the top 50

Share counts compared with the Q2 2026 13F; a split also changes share counts. The latest filing lists more than 50 positions, so a position that left the top 50 may still be held.

How the holdings did against the S&P 500.

1 year: +54.4% /yr; S&P 500 +20.1%
3 years: +43.4% /yr; S&P 500 +20.4%
5 years: +16.4% /yr; S&P 500 +11.6%

A portfolio of the filer's 20 largest 13F positions, weighted by value, bought the trading day after each 13F was filed and held until the next one was: what copying this filer could have earned. 13Fs show long US-listed positions only, so this is an estimate of the stock picks, not the fund's reported returns.

Reported 13F value by quarter.

13F value by quarter
Quarter	13F value	Positions
Q3 2026	$674.7M	301
Q2 2026	$763.4M	306
Q1 2026	$631.7M	305
Q4 2025	$655.9M	306
Q3 2025	$653.4M	299
Q2 2025	$550.0M	298
Q1 2025	$479.4M	303
Q4 2024	$556.1M	307
Q3 2024	$573.7M	302
Q2 2024	$534.7M	302
Q1 2024	$506.7M	306
Q4 2023	$507.9M	315

Questions about Essex Investment Management Co LLC's portfolio

What stocks does Essex Investment Management Co LLC own?

Essex Investment Management Co LLC's latest 13F, for Q3 2026 and filed Oct 19, 2026, lists 301 positions worth $674.7M. The largest are Tower Semiconductor Ltd (TSEM) at 3.1%, Kiniksa Pharmaceuticals Intl (KNSA) at 2.2%, Ligand Pharmaceuticals Inc (LGND) at 1.8%, Adaptive Biotechnologies Corp (ADPT) at 1.7% and Apple Inc (AAPL) at 1.5%.

What did Essex Investment Management Co LLC buy last quarter?

Essex Investment Management Co LLC opened no new positions and grew none by more than 5% among its largest holdings in Q3 2026.

What did Essex Investment Management Co LLC sell last quarter?

In Q3 2026, Essex Investment Management Co LLC cut from its top 50 Tetra Technologies Inc Del (TTI), cut from its top 50 Orion Marine Group Inc Com (ORN), cut from its top 50 Advanced Drain Sys Inc Del (WMS), cut from its top 50 Everus Constr Group (ECG), cut from its top 50 Liquidia Corporation (LQDA), Ouster Inc (OUST) (-32.3% shares), Graham Corp (GHM) (-19.5% shares) and Lincoln Educational Srvcs (LINC) (-18.3% shares), compared with its Q2 2026 filing.

How has Essex Investment Management Co LLC's portfolio performed?

A portfolio copying Essex Investment Management Co LLC's 20 largest 13F holdings each quarter, from the day each filing was public, returned +43.4% a year over the last 3 years, against +20.4% for the S&P 500. Over 1 year: +54.4% against +20.1%. Over 5 years: +16.4% a year against +11.6%.

When is Essex Investment Management Co LLC's next 13F filing due?

13F filings are due 45 days after each quarter ends. Essex Investment Management Co LLC's filing for the quarter ending Dec 31, 2026 is due by Feb 14, 2027; this page updates the day after it is published.

How much money does Essex Investment Management Co LLC manage?

Essex Investment Management Co LLC reported $712.7M of regulatory assets under management on its latest SEC Form ADV. Its 13F, which covers only US-listed stocks and options, totals $674.7M.