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Institutional

WESTFIELD CAPITAL MANAGEMENT CO LP

CIK 0001177719
$23.83B
Reported AUM
250
Positions
Q1 2026
Period
2026-05-11
Filed

The Brief · WESTFIELD CAPITAL MANAGEMENT CO LP · Q1 2026

AI · grounded in 13F

WESTFIELD CAPITAL MANAGEMENT CO LP closed its position in CVLT for a reduction of $132.5M. The fund also exited its position in TEAM for $131.7M and established new positions in LNG for $130.3M and AS for $129.6M. Additionally, the manager increased its stake in INSM by 239.5% and reduced its holding in MASI by 77.6%.

Portfolio · Q1 2026

NVDAASCENDIFIXAAPLFTAIMSFTGOOGLHWMVRTAMZNOther$15.77BWL

Top holdings

#StockIssuerPriceDay %1Y Gr.5Y Gr.Value% of bookΔ shares (QoQ)Status
1NVDANVIDIA CORPORATION$195.042.65%9.52%751.61%$1.10B4.62%HELD
2ASNDUSDASCENDIS PHARMA A/S$1.10B4.62%HELD
3FIXCOMFORT SYS USA INC$1697.8411.70%144.74%2179.41%$856.2M3.59%HELD
4AAPLAPPLE INC$333.43-1.41%65.41%124.96%$795.2M3.34%HELD
5FTAIFTAI AVIATION LTD$197.500.07%36.90%836.75%$697.8M2.93%HELD
6MSFTMICROSOFT CORP$451.1015.51%-13.24%55.41%$610.6M2.56%HELD
7GOOGLALPHABET INC$333.66-0.91%76.18%131.67%$582.8M2.45%HELD
8HWMHOWMET AEROSPACE INC$277.281.65%50.82%785.59%$527.7M2.21%HELD
9VRTVERTIV HOLDINGS CO$227.502.00%57.70%695.55%$481.5M2.02%HELD
10AMZNAMAZON COM INC$235.503.90%9.66%35.70%$474.8M1.99%HELD
11AXONAXON ENTERPRISE INC$525.30-1.11%-29.25%188.83%$451.9M1.90%HELD
12AVGOBROADCOM INC$387.844.73%34.78%753.17%$382.8M1.61%HELD
13LLYELI LILLY & CO$1154.97-4.55%54.61%373.33%$335.3M1.41%HELD
14TPRTAPESTRY INC$152.581.65%43.02%323.83%$310.3M1.30%HELD
15METAMETA PLATFORMS INC$539.03-7.95%-21.66%55.72%$301.4M1.26%HELD
16LPLALPL FINL HLDGS INC$339.170.41%-8.35%133.55%$265.2M1.11%HELD
17MKSIMKS INC.$293.3013.85%217.92%106.68%$240.6M1.01%HELD
18INSMINSMED INC$101.49-1.58%-7.34%259.18%$240.1M1.01%HELD
19PCVXVAXCYTE INC$55.965.62%60.21%101.68%$211.9M0.89%HELD
20RKLBROCKET LAB CORP$64.6810.38%44.34%544.87%$203.7M0.85%HELD
21NFLXNETFLIX INC.$73.17-0.62%-36.85%28.55%$189.4M0.79%HELD
22APGAPI GROUP CORP$39.201.95%10.79%151.33%$187.8M0.79%HELD
23QUREQUANTA SVCS INC$42.195.29%201.90%42.57%$182.2M0.76%HELD
24GEVGE VERNOVA INC$981.989.07%37.44%488.18%$174.0M0.73%HELD
25ARESARES MANAGEMENT CORPORATION$124.12-0.39%-29.45%88.43%$171.6M0.72%HELD
26RYTMRHYTHM PHARMACEUTICALS INC$105.74-0.74%19.75%712.76%$167.8M0.70%HELD
27TSMTAIWAN SEMICONDUCTOR MANUFAC$403.317.64%73.36%267.64%$166.8M0.70%HELD
28MRVLMARVELL TECHNOLOGY INC$183.3012.18%146.73%205.17%$165.7M0.70%HELD
29BEBLOOM ENERGY CORP$207.1226.49%464.05%866.95%$161.4M0.68%HELD
30IOTSAMSARA INC$35.80-7.61%-0.58%97.79%$160.8M0.67%HELD
31AMEAMETEK INC$240.012.02%$159.9M0.67%HELD
32PRPERMIAN RESOURCES CORP$21.001.20%$159.5M0.67%HELD
33DTDYNATRACE INC$44.100.50%$155.7M0.65%HELD
34RVMDREVOLUTION MEDICINES INC$192.176.22%$151.4M0.64%HELD
35NTRANATERA INC$269.666.24%$150.9M0.63%HELD
36FNFABRINET$439.335.99%$148.6M0.62%HELD
37ABVXABIVAX SA$124.334.62%$147.3M0.62%HELD
38NOWSERVICENOW INC$110.07-4.92%$145.8M0.61%HELD
39FTITECHNIPFMC PLC$68.92-3.92%$140.6M0.59%HELD
40RCLROYAL CARIBBEAN GROUP$321.94-0.51%$139.2M0.58%HELD
41HLTHILTON WORLDWIDE HLDGS INC$322.020.09%$139.1M0.58%HELD
42VVISA INC$366.27-0.67%$138.0M0.58%HELD
43CORCENCORA INC$312.23-2.00%$137.3M0.58%HELD
44ITTITT INC$193.001.15%$134.0M0.56%HELD
45CELHCELSIUS HLDGS INC$29.351.63%$133.7M0.56%HELD
46NXTNEXTPOWER INC$96.904.56%$133.5M0.56%HELD
47LNGCHENIERE ENERGY INC$258.06-0.21%$130.3M0.55%HELD
48ASAMER SPORTS INC$36.100.11%$129.6M0.54%HELD
49RRXREGAL REXNORD CORPORATION$202.597.99%$127.7M0.54%HELD
50MSCIMSCI INC$575.74-1.23%$126.0M0.53%HELD
51GHGUARDANT HEALTH INC$152.355.75%$125.9M0.53%HELD
52LYVLIVE NATION ENTERTAINMENT IN$183.56-0.47%$123.6M0.52%HELD
53TSLATESLA INC$308.853.53%$117.5M0.49%HELD
54GLGLOBE LIFE INC$182.981.84%$117.2M0.49%HELD
55BROSDUTCH BROS INC$65.431.27%$117.2M0.49%HELD
56NETCLOUDFLARE INC$283.394.81%$111.7M0.47%HELD
57ROKUROKU INC$145.09-0.17%$111.5M0.47%HELD
58XPOXPO INC$199.26-0.06%$111.3M0.47%HELD
59FITBFIFTH THIRD BANCORP$56.590.04%$110.8M0.46%HELD
60PEVERPURE INC$75.068.39%$110.7M0.46%HELD
61KTOSKRATOS DEFENSE & SEC SOLUTIO$46.175.22%$110.2M0.46%HELD
62AIGAMERICAN INTL GROUP INC$78.89-1.63%$109.8M0.46%HELD
63SNOWSNOWFLAKE INC$298.105.37%$108.4M0.45%HELD
64PRIMPRIMORIS SVCS CORP$85.6514.57%$106.3M0.45%HELD
65JLLJONES LANG LASALLE INC$361.726.39%$105.8M0.44%HELD
66LGNLEGENCE CORP$59.8112.68%$105.1M0.44%HELD
67LEGNLEGEND BIOTECH CORP$19.051.06%$104.3M0.44%HELD
68KEYKEYCORP$22.611.94%$104.1M0.44%HELD
69ROSTROSS STORES INC$252.570.24%$102.2M0.43%HELD
70PLMRPALOMAR HLDGS INC$136.30-4.63%$102.1M0.43%HELD
71PANWPALO ALTO NETWORKS INC$325.683.67%$102.0M0.43%HELD
72FANGDIAMONDBACK ENERGY INC$199.770.32%$99.6M0.42%HELD
73PLTRPALANTIR TECHNOLOGIES INC$122.26-0.60%$98.7M0.41%HELD
74SMTCSEMTECH CORP$114.6110.68%$98.5M0.41%HELD
75WWDWOODWARD INC$356.28-7.56%$97.4M0.41%HELD
76ANETARISTA NETWORKS INC$171.028.26%$95.8M0.40%HELD
77AZOAUTOZONE INC$3006.57-4.32%$95.8M0.40%HELD
78SNSHARKNINJA INC$163.332.58%$95.8M0.40%HELD
79COHRCOHERENT CORP$249.0612.16%$94.5M0.40%HELD
80ALABASTERA LABS INC$299.6920.00%$94.3M0.40%HELD
81BRZEBRAZE INC$25.06-6.60%$93.8M0.39%HELD
82JBLJABIL INC$308.527.45%$92.8M0.39%HELD
83LECOLINCOLN ELEC HLDGS INC$250.22-3.01%$89.2M0.37%HELD
84IMAXIMAX CORP$47.60-2.18%$88.9M0.37%HELD
85WGSGENEDX HOLDINGS CORP$68.968.28%$87.9M0.37%HELD
86GRMNGARMIN LTD$297.550.92%$87.3M0.37%HELD
87CRDOCREDO TECHNOLOGY GROUP HOLDI$201.0813.32%$86.9M0.36%HELD
88FFIVF5 INC$388.750.47%$86.4M0.36%HELD
89EWBCEAST WEST BANCORP INC$130.910.48%$86.0M0.36%HELD
90LTHLIFE TIME GROUP HOLDINGS INC$44.20-3.28%$85.8M0.36%HELD
91BIRKBIRKENSTOCK HOLDING PLC$40.49-2.50%$83.8M0.35%HELD
92ORLYOREILLY AUTOMOTIVE INC$87.36-3.61%$82.0M0.34%HELD
93MSMORGAN STANLEY$210.063.41%$81.7M0.34%HELD
94XENEXENON PHARMACEUTICALS INC$64.191.73%$81.5M0.34%HELD
95ALNYALNYLAM PHARMACEUTICALS INC$81.2M0.34%HELD
96FCFSFIRSTCASH HOLDINGS INC$201.94-0.14%$81.2M0.34%HELD
97IEXIDEX CORP$233.771.85%$80.8M0.34%HELD
98MTZMASTEC INC$324.4412.88%$80.4M0.34%HELD
99HLIHOULIHAN LOKEY INC$128.34-7.72%$78.1M0.33%HELD
100PLXSPLEXUS CORP$241.990.62%$77.9M0.33%HELD
101KRMNKARMAN HLDGS INC$77.2M0.32%HELD
102AITAPPLIED INDL TECHNOLOGIES IN$76.7M0.32%HELD
103TRGPTARGA RES CORP$76.5M0.32%HELD
104CALXCALIX INC$75.7M0.32%HELD
105ADPTADAPTIVE BIOTECHNOLOGIES COR$75.5M0.32%HELD
106WYNNWYNN RESORTS LTD$75.1M0.32%HELD
107CLHCLEAN HARBORS INC$74.9M0.31%HELD
108IDXXIDEXX LABS INC$74.7M0.31%HELD
109VSTVISTRA CORP$74.4M0.31%HELD
110ROKROCKWELL AUTOMATION INC$74.0M0.31%HELD
111GWREGUIDEWIRE SOFTWARE INC$72.8M0.31%HELD
112CHRWC H ROBINSON WORLDWIDE IN$71.3M0.30%HELD
113LOWLOWES COS INC$71.1M0.30%HELD
114NAMSNEWAMSTERDAM PHARMA COMPANY$70.5M0.30%HELD
115CSXCSX CORP$68.1M0.29%HELD
116ONTOONTO INNOVATION INC$67.0M0.28%HELD
117DASHDOORDASH INC$66.7M0.28%HELD
118RRRRED ROCK RESORTS INC$65.5M0.27%HELD
119CWSTCASELLA WASTE SYS INC$65.3M0.27%HELD
120PKGPACKAGING CORP AMER$64.5M0.27%HELD
121WTFCWINTRUST FINL CORP$63.2M0.27%HELD
122MCHPMICROCHIP TECHNOLOGY INC.$62.7M0.26%HELD
123MASIMASIMO CORP$60.7M0.25%HELD
124ZSZSCALER INC$60.0M0.25%HELD
125HQYHEALTHEQUITY INC$59.6M0.25%HELD
126DSGXDESCARTES SYS GROUP INC$57.4M0.24%HELD
127PCORPROCORE TECHNOLOGIES INC$57.1M0.24%HELD
128AVNTAVIENT CORPORATION$57.0M0.24%HELD
129HUBSHUBSPOT INC$56.9M0.24%HELD
130STEPSTEPSTONE GROUP INC$56.2M0.24%HELD
131IBPINSTALLED BLDG PRODS INC$55.2M0.23%HELD
132COCOVITA COCO CO INC$55.2M0.23%HELD
133SAIASAIA INC$54.7M0.23%HELD
134MCOMOODYS CORP$53.9M0.23%HELD
135SNPSSYNOPSYS INC$52.7M0.22%HELD
136PHPARKER-HANNIFIN CORP$52.4M0.22%HELD
137LSCCLATTICE SEMICONDUCTOR CORP$52.3M0.22%HELD
138BLDTOPBUILD COR$52.2M0.22%HELD
139BACBANK AMERICA CORP$52.0M0.22%HELD
140GKOSGLAUKOS CORP$51.9M0.22%HELD
141KKRKKR & CO INC$51.6M0.22%HELD
142CDECOEUR MNG INC$51.4M0.22%HELD
143CRMSALESFORCE INC$50.8M0.21%HELD
144MARMARRIOTT INTL INC NEW$50.1M0.21%HELD
145MDGLMADRIGAL PHARMACEUTICALS INC$49.6M0.21%HELD
146AFRMAFFIRM HLDGS INC$49.5M0.21%HELD
147NXPINXP SEMICONDUCTORS N V$48.8M0.20%HELD
148JBHTHUNT J B TRANS SVCS INC$48.4M0.20%HELD
149DORMDORMAN PRODS INC$48.1M0.20%HELD
150TOSTTOAST INC$47.5M0.20%HELD
151PLPLANET LABS PBC$45.8M0.19%HELD
152TECHBIO-TECHNE CORP$44.7M0.19%HELD
153HOODROBINHOOD MKTS INC$43.9M0.18%HELD
154ENTGENTEGRIS INC$43.6M0.18%HELD
155RIOTRIOT PLATFORMS INC$43.3M0.18%HELD
156FICOFAIR ISAAC CORP$42.6M0.18%HELD
157TLNTALEN ENERGY CORP$42.0M0.18%HELD
158CPAYCORPAY INC$41.6M0.17%HELD
159MDBMONGODB INC$40.4M0.17%HELD
160IONQIONQ INC$39.6M0.17%HELD
161HLNEHAMILTON LANE INC$36.2M0.15%HELD
162MUMICRON TECHNOLOGY INC$33.9M0.14%HELD
163FCXFREEPORT MCMORAN INC$32.0M0.13%HELD
164OPCHOPTION CARE HEALTH INC$31.8M0.13%HELD
165LCLENDINGCLUB ISSUANCE TR SER$30.3M0.13%HELD
166SPXCSPX TECHNOLOGIES INC$29.8M0.13%HELD
167RDNTRADNET INC$29.7M0.12%HELD
168FASTFASTENAL CO$29.6M0.12%HELD
169MTSIMACOM TECH SOLUTIONS HLDGS I$29.4M0.12%HELD
170RGTIRIGETTI COMPUTING INC$26.6M0.11%HELD
171CATCATERPILLAR INC$22.9M0.10%HELD
172CORZCORE SCIENTIFIC INC NEW$22.1M0.09%HELD
173UECURANIUM ENERGY CORP$21.2M0.09%HELD
174DHRDANAHER CORP DEL$20.9M0.09%HELD
175ORKAORUKA THERAPEUTICS INC$15.4M0.06%HELD
176TDGTRANSDIGM GROUP INC$15.0M0.06%HELD
177PTRNPATTERN GROUP INC$14.6M0.06%HELD
178GOOGALPHABET INC$14.5M0.06%HELD
179MLIMUELLER INDS INC$14.0M0.06%HELD
180WMBWILLIAMS COS INC$13.2M0.06%HELD
181APLDAPPLIED DIGITAL CORP$12.9M0.05%HELD
182CIENCIENA CORP$12.3M0.05%HELD
183KOCOCA COLA CO$10.2M0.04%HELD
184SMFGSUMITOMO MITSUI FIN GRP INC$9.0M0.04%HELD
185WMTWALMART INC$8.9M0.04%HELD
186JNJJOHNSON & JOHNSON$8.8M0.04%HELD
187MUFGMITSUBISHI UFJ FINANCIAL GRO$8.8M0.04%HELD
188CMICUMMINS INC$8.3M0.03%HELD
189NEENEXTERA ENERGY INC$8.1M0.03%HELD
190TJXTJX COS INC NEW$7.8M0.03%HELD
191WMT2WELLS FARGO & CO$7.0M0.03%HELD
192ROLROLLINS INC$7.0M0.03%HELD
193HDHOME DEPOT INC$6.7M0.03%HELD
194TMOTHERMO FISHER SCIENTIFIC INC$6.6M0.03%HELD
195TTTRANE TECHNOLOGIES PLC$6.6M0.03%HELD
196MTBM & T BK CORP$6.2M0.03%HELD
197HSYHERSHEY CO$6.1M0.03%HELD
198FCNCAFIRST CTZNS BANCSHARES INC D$6.0M0.03%HELD
199AMGNAMGEN INC$6.0M0.03%HELD
200GSGOLDMAN SACHS GROUP INC$6.0M0.03%HELD
201MCKMCKESSON CORP$6.0M0.03%HELD
202BBVABANCO BILBAO VIZCAYA ARGENTA$5.8M0.02%HELD
203RJFRAYMOND JAMES FINL INC$5.8M0.02%HELD
204MCDMCDONALDS CORP$5.6M0.02%HELD
205MDTMEDTRONIC PLC$5.2M0.02%HELD
206MRKMERCK & CO INC$5.2M0.02%HELD
207CCITIGROUP INC$5.0M0.02%HELD
208HEI/AHEICO CORP NEW$4.2M0.02%HELD
209SCCOSOUTHERN COPPER CORP$4.2M0.02%HELD
210EXPEEXPEDIA GROUP INC$3.9M0.02%HELD
211PFEPFIZER INC$3.8M0.02%HELD
212GILDGILEAD SCIENCES INC$3.7M0.02%HELD
213WSOWATSCO INC$3.6M0.01%HELD
214PEPPEPSICO INC$3.5M0.01%HELD
215DDOMINION ENERGY INC$3.3M0.01%HELD
216CAHCARDINAL HEALTH INC$2.8M0.01%HELD
217ABBVABBVIE INC$2.3M0.01%HELD
218ITGARTNER INC$2.3M0.01%HELD
219ISRGINTUITIVE SURGICAL INC$1.9M0.01%HELD
220IWFISHARES TR$1.7M0.01%HELD
221DXCMDEXCOM INC$1.7M0.01%HELD
222PACKRANPAK HOLDINGS CORP$1.5M0.01%HELD
223RMBSRAMBUS INC DEL$1.2M0.01%HELD
224VUGVANGUARD INDEX FDS$1.1M0.00%HELD
225IWPISHARES TR$1.1M0.00%HELD
226AMDADVANCED MICRO DEVICES INC$1.0M0.00%HELD
227MNDYMONDAY COM LTD$924K0.00%HELD
228GENIGENIUS SPORTS LIMITED$918K0.00%HELD
229IBMINTERNATIONAL BUSINESS MACHS$805K0.00%HELD
230UNHUNITEDHEALTH GROUP INC$749K0.00%HELD
231IVWISHARES TR$734K0.00%HELD
232WCNWASTE CONNECTIONS INC$725K0.00%HELD
233EQTEQT CORP$677K0.00%HELD
234NVONOVO-NORDISK A S$629K0.00%HELD
235WABWABTEC$622K0.00%HELD
236APPAPPLOVIN CORP$501K0.00%HELD
237IJKISHARES TR$494K0.00%HELD
238VRTXVERTEX PHARMACEUTICALS INC$386K0.00%HELD
239BSXBOSTON SCIENTIFIC CORP$374K0.00%HELD
240PODDINSULET CORP$353K0.00%HELD
241CNRCORE NATURAL RESOURCES INC$352K0.00%HELD
242CCJCAMECO CORP$338K0.00%HELD
243AMATAPPLIED MATLS INC$320K0.00%HELD
244IONSIONIS PHARMACEUTICALS INC$263K0.00%HELD
245SRRKSCHOLAR ROCK HLDG CORP$255K0.00%HELD
246AVTXAVALO THERAPEUTICS INC$233K0.00%HELD
247STAGSTAG INDUSTRIAL INC$233K0.00%HELD
248PRAXPRAXIS PRECISION MEDICINES I$213K0.00%HELD
249IMVTIMMUNOVANT INC$213K0.00%HELD
250LUNGPULMONX CORP$142K0.00%HELD

Source: SEC EDGAR · accession 0001177719-26-000018. 13F discloses long positions only — shorts, foreign equities, and options are excluded.