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GW&K Investment Management, LLC — 13F Holdings & Portfolio

CIK 1082917 · latest 13F-HR filed 2026-08-12

Backtest portfolio

GW&K Investment Management, LLC manages $12.80B in 13F-reported U.S. long-equity assets across 1,287 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are MTSI (1.75%), AEIS (1.58%), SPXC (1.27%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 121 new positions and exited 32; 558 existing positions rose in reported value and 243 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.

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AUM
$12.80B

Long-equity book

Holdings
1,287

Distinct positions

Period
2026-06-30

Filed 2026-08-12

Q/Q Activity
+121 / −32 / ↑558 / ↓243

vs 2026-03-31

Portfolio charts

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

Portfolio map

Q2 26
MTSI1.9% · -24%AEIS1.7% · -4%SPXC1.4% · +6%STRL1.3% · -35%ITT1.2% · -4%NOVT1.1% · +4%RBC1.1% · -20%MOG.A1.0% · -5%ENTG1.0% · -6%APG1.0% · -5%TXRH1.0% · +1%FSS0.9% · -3%FN0.9% · +64%POWL0.9% · +104%GMED0.9% · -3%COHR0.9% · -1%GTES0.8% · -5%HALO0.8% · -3%PFGC0.8% · -4%BURL0.8% · -4%AVGO0.8% · -19%IDA0.8% · -4%MSFT0.8% · -1%UMBF0.8% · -4%NBIX0.7% · -4%CVCO0.7% · -6%ESI0.7% · -7%MEDP0.7% · -6%NDSN0.7% · -6%LOPE0.7% · -15%VOYA0.7% · -5%AIT0.7% · -5%SF0.7% · -5%FIX0.7% · -54%JBL0.7% · -36%JAZZ0.7% · -6%BBIO0.7% · +17%SEI0.7% · -2%VCYT0.7% · -1%RHP0.6% · +74%CYTK0.6% · +85%LGND0.6% · +65%DELL0.6% · +15%MGY0.6% · -5%CGNX0.6% · -6%BJ0.6% · +12%CFG0.6% · -2%PM0.6% · -2%DCO0.6% · +22%GBCI0.5% · -4%ABBV0.5% · -11%JPM0.5% · -2%VCEL0.5% · -4%RPM0.5% · -4%MTDR0.5% · -12%INSM0.5% · +1%NVDA0.5% · -1%DORM0.5% · -6%SMTC0.5% · -15%CRNX0.5% · +7%

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

Q1 26 → Q2 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

4 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 = 12.7%

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

Firm Profile & Key People

As of the firm’s regulatory filing dated Mar 26, 2026.

Assets Under Management
$52.78B
Discretionary
$52.78B
Employees
177
Accounts
48,710
Address
222 BERKELEY STREET
15TH FLOOR
BOSTON, MA 02116
Phone
(617) 236-8900
Website
Name Title / Status Ownership Type
CLARE, MICHAEL, JASON ControlPRESIDENT
since Mar 2026
Less than 5%Individual
KOTLER, HAROLD, GILBERT ControlFOUNDER-CHAIRMAN
since Jun 2022
Less than 5%Individual
POWERS, THOMAS, F X ControlCHIEF EXECUTIVE OFFICER
since Jun 2022
5–10%Individual
AMG BOSTON HOLDINGS, LLCMANAGER MEMBER
since Oct 2008
50–75%Domestic Entity
MAGUIRE, BRIAN, TIMOTHYCHIEF FINANCIAL OFFICER
since Jan 2025
Less than 5%Individual
ROUSE, DAVID, JOHNCHIEF COMPLIANCE OFFICER
since Mar 2021
Less than 5%Individual
AFFILIATED MANAGERS GROUP, INC. Control
Indirect owner via AMG GWK HOLDINGS, LLC
MANAGER AND SOLE MEMBER
since Jun 2014
75% or moreDomestic Entity
AMG GWK HOLDINGS, LLC Control
Indirect owner via AMG BOSTON HOLDINGS, LLC
MANAGER AND SERIES A MEMBER
since Sep 2014
75% or moreDomestic Entity
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 26, 2026 filing
  • No longer listedROBERTS, III, THOMAS, WILLIAMS · CO-CHIEF EXECUTIVE OFFICER · 5–10% · control person · listed since Jun 2022
  • AddedCLARE, MICHAEL, JASON · PRESIDENT · Less than 5% · control person
  • ChangedPOWERS, THOMAS, F X · title CO-CHIEF EXECUTIVE OFFICER → CHIEF EXECUTIVE OFFICER
Mar 27, 2025 filing
  • AddedMAGUIRE, BRIAN, TIMOTHY · CHIEF FINANCIAL OFFICER · Less than 5%
Mar 29, 2023 filing
  • ChangedKOTLER, HAROLD, GILBERT · title CHIEF EXECUTIVE OFFICER → FOUNDER-CHAIRMAN
  • ChangedPOWERS, THOMAS, F X · title CO-PRESIDENT → CO-CHIEF EXECUTIVE OFFICER
  • ChangedROBERTS, III, THOMAS, WILLIAMS · title CO-PRESIDENT → CO-CHIEF EXECUTIVE OFFICER
Mar 26, 2021 filing
  • AddedROUSE, DAVID, JOHN · CHIEF COMPLIANCE OFFICER · Less than 5%
  • ChangedROBERTS, III, THOMAS, WILLIAMS · title CO-PRESIDENT & CHIEF COMPLIANCE OFFICER → CO-PRESIDENT
Mar 28, 2018 filing
  • ChangedKOTLER, HAROLD, GILBERT · ownership 5–10% → Less than 5%
Mar 30, 2017 filing
  • No longer listedAFFILIATED MANAGERS GROUP, INC. · MANAGER AND SOLE MEMBER · 75% or more · indirect via AMG GW&K HOLDINGS, LLC · control person · listed since Jun 2014
  • AddedAFFILIATED MANAGERS GROUP, INC. · MANAGER AND SOLE MEMBER · 75% or more · indirect via AMG GWK HOLDINGS, LLC · control person
  • ChangedAMG BOSTON HOLDINGS, LLC · title MANAGER → MANAGER MEMBER
Mar 21, 2016 filing
  • No longer listedAFFILIATED MANAGERS GROUP, INC. · MANAGER AND SOLE MEMBER · 75% or more · indirect via AMG BOSTON HOLDINGS, LLC · control person · listed since Jun 2014
  • AddedAFFILIATED MANAGERS GROUP, INC. · MANAGER AND SOLE MEMBER · 75% or more · indirect via AMG GW&K HOLDINGS, LLC · control person
Mar 30, 2015 filing
  • AddedAMG GWK HOLDINGS, LLC · MANAGER AND SERIES A MEMBER · 75% or more · indirect via AMG BOSTON HOLDINGS, LLC · control person
  • ChangedAFFILIATED MANAGERS GROUP, INC. · indirect via AMG BOSTON HOLDINGS, LLC: title SHAREHOLDER → MANAGER AND SOLE MEMBER; now a control person
  • ChangedAMG BOSTON HOLDINGS, LLC · title MANAGING MEMBER → MANAGER
Mar 14, 2014 filing
  • ChangedAMG BOSTON HOLDINGS, LLC · ownership 75% or more → 50–75%
  • ChangedKOTLER, HAROLD, GILBERT · ownership Less than 5% → 5–10%
  • ChangedPOWERS, THOMAS, F X · ownership Less than 5% → 5–10%
  • ChangedROBERTS, III, THOMAS, WILLIAMS · ownership Less than 5% → 5–10%
Mar 15, 2013 filing
  • ChangedAFFILIATED MANAGERS GROUP, INC. · indirect via AMG BOSTON HOLDINGS, LLC: no longer a control person
  • ChangedAMG BOSTON HOLDINGS, LLC · no longer a control person
Older changes (1 more filing)
Mar 30, 2012 filing (earliest on record)
  • ListedAFFILIATED MANAGERS GROUP, INC. · SHAREHOLDER · 75% or more · indirect via AMG BOSTON HOLDINGS, LLC · control person
  • ListedAMG BOSTON HOLDINGS, LLC · MANAGING MEMBER · 75% or more · control person
  • ListedKOTLER, HAROLD, GILBERT · CHIEF EXECUTIVE OFFICER · Less than 5% · control person
  • ListedPOWERS, THOMAS, F X · CO-PRESIDENT · Less than 5% · control person
  • ListedROBERTS, III, THOMAS, WILLIAMS · CO-PRESIDENT & CHIEF COMPLIANCE OFFICER · Less than 5% · 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.

GW&K Investment Management, LLC Holdings (2026-06-30)

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 MACOM TECHNOLOGY SOLUTIONS H MTSI 55405Y100 $223.6M 1.75% 587,948 SH
2 ADVANCED ENERGY INDUSTRIES AEIS 007973100 $201.7M 1.58% 541,066 SH
3 SPX TECHNOLOGIES INC SPXC 78473E103 $162.6M 1.27% 663,167 SH
4 STERLING INFRASTRUCTURE INC STRL 859241101 $154.8M 1.21% 184,432 SH
5 ITT INC ITT 45073V108 $140.4M 1.10% 710,072 SH
6 NOVANTA INC NOVT 67000B104 $136.1M 1.06% 839,091 SH
7 RBC BEARINGS INC RBC 75524B104 $133.6M 1.04% 207,393 SH
8 MOOG INC-CLASS A MOG.A 615394202 $123.6M 0.97% 291,657 SH
9 ENTEGRIS INC ENTG 29362U104 $116.8M 0.91% 649,599 SH
10 API GROUP CORP APG 00187Y100 $116.2M 0.91% 2,744,289 SH
11 TEXAS ROADHOUSE INC TXRH 882681109 $114.8M 0.90% 594,086 SH
12 FABRINET FN G3323L100 $113.2M 0.88% 201,313 SH
13 FEDERAL SIGNAL CORP FSS 313855108 $110.8M 0.87% 862,199 SH
14 POWELL INDUSTRIES INC POWL 739128106 $109.5M 0.86% 382,538 SH
15 GLOBUS MEDICAL INC - A GMED 379577208 $107.2M 0.84% 1,356,729 SH
16 COHERENT CORP COHR 19247G107 $105.6M 0.83% 267,756 SH
17 BROADCOM INC AVGO 11135F101 $102.8M 0.80% 272,092 SH
18 MICROSOFT CORP MSFT 594918104 $100.4M 0.78% 269,177 SH
19 HALOZYME THERAPEUTICS INC HALO 40637H109 $99.2M 0.78% 1,267,823 SH
20 GATES INDUSTRIAL CORP PLC GTES G39108108 $98.8M 0.77% 3,532,896 SH
21 PERFORMANCE FOOD GROUP CO PFGC 71377A103 $97.6M 0.76% 873,353 SH
22 BURLINGTON STORES INC BURL 122017106 $96.0M 0.75% 303,167 SH
23 IDACORP INC IDA 451107106 $92.9M 0.73% 613,875 SH
24 NEUROCRINE BIOSCIENCES INC NBIX 64125C109 $88.9M 0.69% 527,491 SH
25 UMB FINANCIAL CORP UMBF 902788108 $88.4M 0.69% 619,450 SH
26 MEDPACE HOLDINGS INC MEDP 58506Q109 $85.8M 0.67% 161,978 SH
27 CAVCO INDUSTRIES INC CVCO 149568107 $85.7M 0.67% 139,466 SH
28 ELEMENT SOLUTIONS INC ESI 28618M106 $84.1M 0.66% 1,760,960 SH
29 GRAND CANYON EDUCATION INC LOPE 38526M106 $83.1M 0.65% 580,473 SH
30 NORDSON CORP NDSN 655663102 $82.0M 0.64% 271,658 SH
31 APPLIED INDUSTRIAL TECH INC AIT 03820C105 $81.5M 0.64% 241,103 SH
32 SOLARIS ENERGY INFRASTRUCTUR SEI 83418M103 $80.1M 0.63% 994,954 SH
33 STIFEL FINANCIAL CORP SF 860630102 $80.0M 0.63% 1,147,122 SH
34 VOYA FINANCIAL INC VOYA 929089100 $79.6M 0.62% 878,936 SH
35 VERACYTE INC VCYT 92337F107 $79.3M 0.62% 1,349,759 SH
36 BRIDGEBIO PHARMA INC BBIO 10806X102 $78.9M 0.62% 1,058,960 SH
37 JABIL INC JBL 466313103 $78.7M 0.61% 204,110 SH
38 COMFORT SYSTEMS USA INC FIX 199908104 $77.3M 0.60% 38,984 SH
39 JAZZ PHARMACEUTICALS PLC JAZZ G50871105 $76.7M 0.60% 318,498 SH
40 DELL TECHNOLOGIES -C DELL 24703L202 $76.2M 0.60% 176,499 SH
41 LIGAND PHARMACEUTICALS LGND 53220K504 $74.9M 0.59% 236,998 SH
42 RYMAN HOSPITALITY PROPERTIES RHP 78377T107 $73.4M 0.57% 571,116 SH
43 CYTOKINETICS INC CYTK 23282W605 $73.3M 0.57% 860,627 SH
44 CITIZENS FINANCIAL GROUP CFG 174610105 $72.4M 0.57% 1,033,943 SH
45 PHILIP MORRIS INTERNATIONAL PM 718172109 $70.8M 0.55% 391,260 SH
46 ABBVIE INC ABBV 00287Y109 $69.4M 0.54% 275,739 SH
47 JPMORGAN CHASE & CO JPM 46625H100 $69.1M 0.54% 211,142 SH
48 MAGNOLIA OIL & GAS CORP - A MGY 559663109 $68.7M 0.54% 2,687,502 SH
49 COGNEX CORP CGNX 192422103 $68.2M 0.53% 942,321 SH
50 BJS WHOLESALE CLUB HOLDINGS BJ 05550J101 $67.3M 0.53% 771,755 SH
Filing History
Period Filed AUM Holdings Accession
2026-06-30 2026-08-12 $12.80B 1,287 0001082917-26-000003
2026-03-31 2026-05-13 $11.34B 1,197 0001082917-26-000002
2025-12-31 2026-02-11 $11.56B 1,178 0001082917-26-000001
2025-09-30 2025-11-12 $11.30B 1,179 0001082917-25-000007
Filer Information
Address
222 BERKELEY ST SUITE 1500
BOSTON, MA 02116
Phone
(617) 236-8900
Filing Manager
GW&K Investment Management, LLC
BOSTON, MA
Signatory
David Rouse
Chief Compliance Officer