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SEC Form 13F

WESTFIELD CAPITAL MANAGEMENT CO LP 13F Holdings

Inspect WESTFIELD CAPITAL MANAGEMENT CO LP's 2026-06-30 SEC 13F positions, public filing date, amendments and original receipt.

As of 2026-08-13T03:59:59.999Z

Report period
2026-06-30
Publicly available
2026-08-13
Reported value
$30,614,527,190
Positions
278
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Disclosed positions

Largest disclosed position values

Scale: 0 to 1,616,700,000 USD · zero baseline

Largest disclosed position values

  • NVDA · COM+1,616,712,338 USD
  • GOOGL · CAP STK CL A+1,339,806,415 USD
  • ASND · ORD SHS+1,279,793,795 USD
  • AXON · COM+836,144,444 USD
  • FTAI · SHS+794,608,199 USD
  • AAPL · COM+744,747,287 USD
  • FIX · COM+704,451,409 USD
  • AVGO · COM+587,976,343 USD
  • MSFT · COM+527,559,770 USD
  • HWM · COM+516,608,027 USD

Reported underlying-position values for 2026-06-30, publicly available 2026-08-13. Put/call values are not option premiums; this subset is not a complete portfolio allocation. Exact issuer, class and unit remain in the table. Showing the first 10 of 50 recorded values; the complete table remains available below.

Inspect all 50 displayed rows: Disclosed positions

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NVIDIA CORPORATIONNVDACOM$1,616,712,3388,079,926SHNone
ALPHABET INCGOOGLCAP STK CL A$1,339,806,4153,749,074SHNone
ASCENDIS PHARMA A/SASNDORD SHS$1,279,793,7954,798,267SHNone
AXON ENTERPRISE INCAXONCOM$836,144,4441,491,490SHNone
FTAI AVIATION LTDFTAISHS$794,608,1992,937,228SHNone
APPLE INCAAPLCOM$744,747,2872,573,774SHNone
COMFORT SYS USA INCFIXCOM$704,451,409355,433SHNone
BROADCOM INCAVGOCOM$587,976,3431,556,522SHNone
MICROSOFT CORPMSFTCOM$527,559,7701,414,294SHNone
HOWMET AEROSPACE INCHWMCOM$516,608,0271,921,476SHNone
ELI LILLY & COLLYCOM$499,840,862416,732SHNone
SNOWFLAKE INCSNOWCOM SHS$441,938,6471,736,498SHNone
MKS INC.MKSICOM$413,048,645928,617SHNone
META PLATFORMS INCMETACL A$381,566,445677,389SHNone
VERTIV HOLDINGS COVRTCOM CL A$353,021,1611,054,361SHNone
GE VERNOVA INCGEVCOM$283,461,275241,272SHNone
MICRON TECHNOLOGY INCMUCOM$263,412,188228,203SHNone
VISA INCVCOM CL A$261,572,839762,403SHNone
API GROUP CORPAPGCOM STK$260,634,6476,154,301SHNone
TAPESTRY INCTPRCOM$248,343,8351,696,569SHNone
RHYTHM PHARMACEUTICALS INCRYTMCOM$245,220,3032,208,595SHNone
LIFE TIME GROUP HOLDINGS INCLTHCOMMON STOCK$244,846,1735,995,254SHNone
TAIWAN SEMICONDUCTOR MANUFACTSMSPONSORED ADS$244,037,920510,999SHNone
GUARDANT HEALTH INCGHCOM$243,717,5841,624,459SHNone
QUANTA SVCS INCPWRCOM$238,685,542331,489SHNone
SERVICENOW INCNOWCOM$235,661,9892,373,711SHNone
ADVANCED MICRO DEVICES INCAMDCOM$234,153,542403,081SHNone
PALO ALTO NETWORKS INCPANWCOM$224,504,060658,331SHNone
WOODWARD INCWWDCOM$223,996,287526,505SHNone
ARISTA NETWORKS INCANETCOM SHS$223,748,3101,317,096SHNone
LPL FINL HLDGS INCLPLACOM$223,389,290793,061SHNone
ROCKET LAB CORPRKLBCOM$214,888,6212,114,005SHNone
AMER SPORTS INCASCOM SHS$214,712,1796,344,923SHNone
CLOUDFLARE INCNETCL A COM$204,931,901835,502SHNone
AMAZON COM INCAMZNCOM$204,926,241859,806SHNone
GARMIN LTDGRMNSHS$204,535,458861,057SHNone
REGAL REXNORD CORPORATIONRRXCOM$204,123,113856,976SHNone
NATERA INCNTRACOM$197,243,187726,628SHNone
MORGAN STANLEYMSCOM NEW$196,614,709940,560SHNone
CARPENTER TECHNOLOGY CORPCRSCOM$193,738,341314,082SHNone
SAMSARA INCIOTCOM CL A$189,276,3735,836,459SHNone
DYNATRACE INCDTCOM NEW$186,583,6454,249,229SHNone
CATERPILLAR INCCATCOM$185,952,922174,620SHNone
SEMTECH CORPSMTCCOM$183,419,4551,133,268SHNone
AMETEK INCAMECOM$175,115,699723,798SHNone
ABIVAX SAABVXSPONSORED ADS$174,547,2801,309,825SHNone
INSMED INCINSMCOM PAR $.01$173,743,7951,629,561SHNone
ITT INCITTCOM$164,216,344830,382SHNone
GILEAD SCIENCES INCGILDCOM$162,679,0711,287,629SHNone
PTC THERAPEUTICS INCPTCTCOM$159,563,6451,956,156SHNone

Largest 50 positions by reported value; the filing may contain more positions.

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NVIDIA CORPORATIONNVDACOM$1,616,712,3388,079,926SHNone

First displayed source row from Disclosed positions. The full bounded history and coverage notes remain below.

The displayed observation date is 2026-06-30 and its public availability date is 2026-08-13. Subtracting those calendar dates gives 44 days of disclosure lag. Historical public research can use the record from the availability date, rather than backdating knowledge to the observation date. The calendar-day difference does not assert an intraday publication time.

Read the amount together with its Unit and Option columns. A reported put or call position is not an option premium paid, and a quarterly holding is not a purchase made on its public filing date. Check every accession in the effective amendment lineage below: a retained holding can originate in an earlier filing rather than the latest linked amendment.

Open the linked original receipts to verify the row, then inspect a second record before drawing a pattern. This public filing observation supplies source evidence, not a completed copy-trading return.

How amendments affect these holdings

This view uses 1 effective filing version(s). A restatement replaces the previous book; a new-holdings amendment adds positions. 2 positions lack a resolved ticker and 0 positions are put or call entries.

The displayed holdings combine the effective filing versions listed here. The latest receipt linked below identifies the current projection version; it is not proof that every retained holding originated in that latest amendment. Inspect all effective accessions when verifying a position's source.

A 13F is a delayed quarterly snapshot of disclosed holdings. It is not a complete trade ledger and does not reveal every position in a manager's portfolio. Option values refer to the reported underlying position rather than a traded option premium.

Show the table · 1 row, 2 columns
Effective SEC accessionRole in this view
0001177719-26-000021Latest effective version

Quarter end and public filing date

Use the filing's public availability date when constructing a historical observation. The quarter-end report period is earlier and cannot be substituted for when the public learned the holdings.