DOSSIER · 13F-HR · Q3 2026

ESSEX INVESTMENT MANAGEMENT CO LLC

$675M in tracked AUM across 301 positions as of Q3 2026.

EI
CIK 0000201772 · last filed Sep 30, 2026
Total AUM
$675M
as of Q3 2026
Holdings
301
—
positions
Whale Score
47
47
tracked
Activity
—
no data
changes this Q
AI Analysis · Q3 2026

Heavy turnover in Essex Investment Management's $631.7 million, 305-position small-cap growth book comes with a caveat — two of the listed "new" and "sold" pairs are data artifacts, not trades: HCI Group appears as both an $8.9 million new position and an $11.3 million sold position under two different CUSIPs, and Argan Inc shows the identical pattern ($8.8 million new vs. $8.7 million sold) — both almost certainly CUSIP reissuances for companies Essex never actually exited. Set those aside, and the real rotation is eight genuine new names (Amprius Technologies, Cohu, Oceaneering International, Bioventus, Novocure, Arteris, ASML, and Syndax Pharmaceuticals) against eight genuine full exits (Beta Bionics, EverQuote, Universal Insurance Holdings, Xeris Biopharma, Salesforce, Pegasystems, Ocular Therapeutix, and AngioDynamics). The largest real trim was Tower Semiconductor, cut 40% in shares for a genuine $13.5 million reduction, still the portfolio's top holding at 3.2%.

Two CUSIP artifacts inflate the apparent turnover

Before reading this quarter's changes as trading activity, two pairs need a caveat. HCI Group shows up as a new $8.9 million position (CUSIP 40416E103) in the same quarter a $11.3 million HCI Group position under CUSIP 40416E107 is listed as fully sold. Argan Inc shows the identical shape: a new $8.8 million position (CUSIP 04010E109) against a $8.7 million sold position (CUSIP 00401E112). Same companies, nearly identical dollar amounts, different CUSIPs, same quarter — both read as CUSIP reissuances rather than Essex actually exiting and re-entering either name.

Analysis generated by 13F Insight from SEC Form 13F filing data · Q3 2026. Methodology

Quarter at a glance — Q3 2026

Position-change comparison pending.

No quarter-over-quarter changes available.

Top 10 holdings

By portfolio weight as of Q3 2026.

#HoldingValueSharesWeight
01
M87915274
TOWER SEMICONDUCTOR LTD
$21M92K3.1%
02
G52694109
KINIKSA PHARMACEUTICALS INTL P
$15M202K2.2%
03
LGND
LIGAND PHARMACEUTICALS INC
$12M39K1.8%
04
ADPT
ADAPTIVE BIOTECHNOLOGIES CORP
$12M402K1.7%
05
AAPL
APPLE INC
$10M31K1.5%
06
CECO
CECO ENVIRONMENTAL CORP
$10M146K1.5%
07
HCI
HCI GROUP INC
$9M54K1.4%
08
DRS
LEONARDO DRS INC
$9M242K1.3%
09
MIRM
MIRUM PHARMACEUTICALS INC
$9M102K1.3%
10
COHU
COHU INC
$9M127K1.3%

Filing history

2026Q3Sep 30
$675M▼ 11.6%
301 positionsView →
2026Q2Jun 30
$763M▲ 20.8%
306 positionsView →
2026Q1Mar 31
$632M▼ 3.7%
305 positionsView →
2025Q4Dec 31
$656M▲ 0.4%
306 positionsView →
2025Q3Sep 30
$653M▲ 18.8%
299 positionsLocked
2025Q2Jun 30
$550M▲ 14.7%
298 positionsLocked
2025Q1Mar 31
$479M▼ 13.8%
303 positionsLocked
2024Q4Dec 31
$556M▼ 3.1%
307 positionsLocked
2024Q3Sep 30
$574M▲ 7.3%
302 positionsLocked
2024Q2Jun 30
$535M▲ 5.5%
302 positionsLocked
2024Q1Mar 31
$507M▼ 0.2%
306 positionsLocked
2023Q4Dec 31
$508M▼ 17.1%
315 positionsLocked
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