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FRONTIER CAPITAL MANAGEMENT CO LLC — 13F Holdings & Portfolio

CIK 351173 · latest 13F-HR filed 2026-08-14

Backtest portfolio

FRONTIER CAPITAL MANAGEMENT CO LLC manages $10.73B in 13F-reported U.S. long-equity assets across 300 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are FTAI (2.98%), GVA (1.65%), ALK (1.65%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 33 new positions, exited 24, added to 134, and trimmed 99.

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.

Filer Information
Address
99 SUMMER ST
BOSTON, MA 02110
Phone
(617) 261-0777
Filing Manager
FRONTIER CAPITAL MANAGEMENT CO LLC
Boston, MA
Signatory
Robert E. Phay, Jr.
Chief Compliance Officer
Loading holdings…
AUM

$10.73B

Long-equity book

Holdings

300

Distinct positions

Period

2026-06-30

Filed 2026-08-14

Q/Q Activity

+33 / −24 / ↑134 / ↓99

vs 2026-03-31

Firm Profile & Key People
Name Title / Status Ownership Type

Top Adds (vs prior quarter)

  • APPLIED OPTOELECTRONICS INC$120.5M +501.2%
  • LATTICE SEMICONDUCTOR CORP$69.6M +123.9%
  • FTAI AVIATION LTD$59.9M +23.0%
  • MONGODB INC$59.8M +113.9%
  • INSULET CORP$58.6M +161.8%
Show all 134 →

Top Trims

  • DARLING INGREDIENTS INC-$108.5M -71.5%
  • CIRCLE INTERNET GROUP INC-$84.8M -57.4%
  • SILA REALTY TRUST INC-$52.4M -82.1%
  • APOGEE THERAPEUTICS INC-$49.3M -55.0%
  • AMENTUM HOLDINGS INC-$42.9M -33.4%
Show all 99 →

New Positions

  • DYNATRACE INC$71.8M
  • PRIMORIS SVCS CORP$46.5M
  • STANDARDAERO INC$43.3M
  • ALKERMES PLC$34.6M
  • ETORO GROUP LTD$32.8M
Show all 33 →

Exited Positions

  • MARVELL TECHNOLOGY INC$53.6M
  • NUVALENT INC$40.5M
  • DIODES INC$40.4M
  • QUIDELORTHO CORP$28.8M
  • DOMINOS PIZZA INC$22.5M
Show all 24 →
All Holdings

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 FTAI AVIATION LTD FTAI G3730V105 $320.2M 2.98% 1,183,492 SH
2 GRANITE CONSTR INC GVA 387328107 $176.9M 1.65% 1,118,881 SH
3 ALASKA AIR GROUP INC ALK 011659109 $176.7M 1.65% 3,384,643 SH
4 APPLIED OPTOELECTRONICS INC AAOI 03823U102 $144.5M 1.35% 975,318 SH
5 AKAMAI TECHNOLOGIES INC AKAM 00971T101 $134.4M 1.25% 1,136,573 SH
6 ASHLAND INC ASH 044186104 $131.8M 1.23% 1,999,908 SH
7 LATTICE SEMICONDUCTOR CORP LSCC 518415104 $125.7M 1.17% 821,848 SH
8 POPULAR INC BPOP 733174700 $119.1M 1.11% 725,227 SH
9 MONGODB INC MDB 60937P106 $112.2M 1.05% 334,098 SH
10 UNITED THERAPEUTICS CORP DEL UTHR 91307C102 $112.1M 1.04% 206,808 SH
11 KNIGHT-SWIFT TRANSN HLDGS IN KNX 499049104 $109.9M 1.02% 1,410,955 SH
12 EAGLE MATLS INC EXP 26969P108 $103.2M 0.96% 458,621 SH
13 STRIDE INC LRN 86333M108 $102.8M 0.96% 1,191,710 SH
14 XPO INC XPO 983793100 $102.6M 0.96% 499,601 SH
15 BRIDGEBIO PHARMA INC BBIO 10806X102 $102.3M 0.95% 1,373,057 SH
16 LIBERTY ENERGY INC LBRT 53115L104 $97.4M 0.91% 3,720,666 SH
17 SANMINA CORP SANM 801056102 $95.7M 0.89% 378,111 SH
18 ULTRA CLEAN HLDGS INC UCTT 90385V107 $95.2M 0.89% 667,532 SH
19 ULTRAGENYX PHARMACEUTICAL IN RARE 90400D108 $95.1M 0.89% 2,847,936 SH
20 INSULET CORP PODD 45784P101 $94.8M 0.88% 622,506 SH
21 MODINE MFG CO MOD 607828100 $91.8M 0.86% 343,868 SH
22 FLOWSERVE CORP FLS 34354P105 $91.5M 0.85% 1,233,291 SH
23 KIRBY CORP KEX 497266106 $90.6M 0.84% 666,554 SH
24 ALLEGIANT TRAVEL CO ALGT 01748X102 $90.0M 0.84% 765,347 SH
25 EVERPURE INC P 74624M102 $88.2M 0.82% 1,120,040 SH
26 AMENTUM HOLDINGS INC AMTM 023939101 $85.7M 0.80% 4,143,971 SH
27 KYMERA THERAPEUTICS INC KYMR 501575104 $85.0M 0.79% 740,866 SH
28 INSMED INC INSM 457669307 $84.8M 0.79% 795,242 SH
29 ATI INC ATI 01741R102 $82.8M 0.77% 419,968 SH
30 RENASANT CORP RNST 75970E107 $75.7M 0.71% 1,778,953 SH
31 ASTERA LABS INC ALAB 04626A103 $74.7M 0.70% 154,601 SH
32 ROYAL CARIBBEAN GROUP RCL V7780T103 $74.3M 0.69% 233,963 SH
33 PALVELLA THERAPEUTICS INC NE PVLA 697947109 $73.2M 0.68% 478,833 SH
34 DYNATRACE INC DT 268150109 $71.8M 0.67% 1,635,587 SH
35 INDIE SEMICONDUCTOR INC INDI 45569U101 $71.5M 0.67% 15,914,169 SH
36 AGREE RLTY CORP ADC 008492100 $71.4M 0.67% 943,005 SH
37 INTUITIVE MACHINES INC LUNR 46125A100 $67.9M 0.63% 3,173,434 SH
38 JAZZ PHARMACEUTICALS PLC JAZZ G50871105 $66.8M 0.62% 277,279 SH
39 SAIA INC SAIA 78709Y105 $63.8M 0.59% 151,477 SH
40 ENTEGRIS INC ENTG 29362U104 $63.3M 0.59% 351,950 SH
41 FIRST BANCORP CORPORATION FBP 318672706 $63.1M 0.59% 2,422,265 SH
42 CIRCLE INTERNET GROUP INC CRCL 172573107 $62.9M 0.59% 1,004,783 SH
43 HUBBELL INC HUBB 443510607 $62.8M 0.59% 119,997 SH
44 AXSOME THERAPEUTICS INC. AXSM 05464T104 $62.2M 0.58% 254,280 SH
45 FLEX LTD FLEX Y2573F102 $61.9M 0.58% 382,135 SH
46 WINTRUST FINL CORP WTFC 97650W108 $61.8M 0.58% 384,593 SH
47 TIDEWATER INC NEW TDW 88642R109 $59.6M 0.56% 894,796 SH
48 ATMUS FILTRATION TECHNOLOGIE ATMU 04956D107 $59.0M 0.55% 1,157,930 SH
49 JABIL INC JBL 466313103 $58.7M 0.55% 152,187 SH
50 BUILDERS FIRSTSOURCE INC BLDR 12008R107 $58.3M 0.54% 651,389 SH
Filing History
Period Filed AUM Holdings Accession
2026-06-30 2026-08-14 $10.73B 300 0001172661-26-003509
2026-03-31 2026-05-15 $9.73B 291 0001172661-26-002082
2025-12-31 2026-02-17 $9.42B 295 0001172661-26-000845
2025-09-30 2025-11-14 $11.15B 297 0001172661-25-004908