William Blair Investment Management, LLC Top Holdings and 13F Report (2026) About William Blair Investment Management, LLCInvestment ActivityWilliam Blair Investment Management, LLC has $30.26 billion in total holdings as of March 31, 2026.William Blair Investment Management, LLC owns shares of 413 different stocks, but just 114 companies or ETFs make up 80% of its holdings.Approximately 12.97% of the portfolio was purchased this quarter.About 25.72% of the portfolio was sold this quarter.This quarter, William Blair Investment Management, LLC has purchased 413 new stocks and bought additional shares in 156 stocks.William Blair Investment Management, LLC sold shares of 205 stocks and completely divested from 47 stocks this quarter.Largest Holdings Taiwan Semiconductor Manufacturing $1,865,444,875NVIDIA $1,559,442,318Apple $1,221,347,410Microsoft $1,072,301,833Alphabet $720,224,207 Largest New Holdings this Quarter G0593M107 - AstraZeneca $377,341,483 Holding00971T101 - Akamai Technologies $185,949,041 Holding099724106 - BorgWarner $156,489,204 Holding032095101 - Amphenol $136,133,786 Holding739276103 - Power Integrations $121,890,662 Holding Largest Purchases this Quarter AstraZeneca 1,942,155 shares (about $377.34M)Akamai Technologies 1,619,060 shares (about $185.95M)BorgWarner 2,884,062 shares (about $156.49M)Amphenol 1,077,434 shares (about $136.13M)Power Integrations 2,380,677 shares (about $121.89M) Largest Sales this Quarter NVIDIA 1,686,911 shares (about $294.20M)Ciena 700,014 shares (about $271.77M)Amazon.com 1,223,374 shares (about $254.79M)Microsoft 593,520 shares (about $219.70M)Alphabet 650,368 shares (about $187.02M) Sector Allocation Over TimeMap of 500 Largest Holdings ofWilliam Blair Investment Management, LLC Selling Neutral Buying Latest 13F Holdings and Changes Since Previous Quarterly FilingIssuer NameHoldings ValueApproximate Purchase/SaleChange in SharesShares Held% of PortfolioSectorTSMTaiwan Semiconductor Manufacturing$1,865,444,875$157,892,767 ▼-7.8%5,518,2606.2%Computer and TechnologyNVDANVIDIA$1,559,442,318$294,197,292 ▼-15.9%8,941,7565.2%Computer and TechnologyAAPLApple$1,221,347,410$160,368,637 ▼-11.6%4,812,4334.0%Computer and TechnologyMSFTMicrosoft$1,072,301,833$219,703,307 ▼-17.0%2,896,7823.5%Computer and TechnologyGOOGLAlphabet$720,224,207$187,019,820 ▼-20.6%2,504,6052.4%Computer and TechnologyAVGOBroadcom$681,404,288$103,702,265 ▼-13.2%2,201,5582.3%Computer and TechnologyAMZNAmazon.com$658,889,012$254,792,103 ▼-27.9%3,163,6292.2%Retail/WholesaleMETAMeta Platforms$579,637,212$99,348,610 ▼-14.6%1,013,1221.9%Computer and TechnologyMAMastercard$529,964,838$12,139,738 ▼-2.2%1,060,6511.8%Business ServicesAZNCFAstraZeneca$377,341,483$377,341,483 ▲New Holding1,942,1551.2%MedicalLINDE PLC$315,470,927$3,535,760 ▼-1.1%636,3381.0%SHSCGCarlyle Group$304,910,650$40,202,071 ▼-11.6%6,301,1091.0%FinanceCOSTCostco Wholesale$301,388,189$25,907,180 ▼-7.9%302,4681.0%Retail/WholesaleITUBItau Unibanco$265,626,612$40,802,627 ▼-13.3%31,684,7080.9%FinanceTWSTTwist Bioscience$250,416,999$32,537,467 ▼-11.5%5,269,7180.8%MedicalNOWServiceNow$247,952,244$23,297,295 ▲10.4%2,371,6140.8%Computer and TechnologyPRIMO BRANDS CORPORATION$245,848,095$8,073,777 ▲3.4%13,056,1920.8%CLASS A COM SHSMLIMueller Industries$233,757,973$36,544,388 ▲18.5%2,109,7290.8%IndustrialsINTUIntuit$230,776,974$39,495,786 ▲20.6%533,7360.8%Computer and TechnologyMNSTMonster Beverage$212,687,998$59,852,105 ▼-22.0%2,935,2470.7%Consumer StaplesAMDAdvanced Micro Devices$212,094,897$60,408,945 ▼-22.2%1,042,5940.7%Computer and TechnologyBAPCredicorp$211,203,994$49,087,147 ▼-18.9%622,6900.7%FinanceAAgilent Technologies$204,681,180$30,460,585 ▼-13.0%1,795,7640.7%MedicalORLYO'Reilly Automotive$204,008,239$71,214,673 ▼-25.9%2,210,0340.7%Retail/WholesaleBWXTBWX Technologies$200,764,601$25,728,523 ▼-11.4%981,7820.7%AerospaceTRUTransUnion$200,041,262$74,331,383 ▼-27.1%2,891,1870.7%Business ServicesONTOOnto Innovation$197,731,160$156,340,036 ▼-44.2%964,2130.7%Computer and TechnologyIDXXIDEXX Laboratories$197,572,324$50,403,219 ▼-20.3%351,6210.7%MedicalNXTNextpower$195,591,049$31,306,232 ▲19.1%1,622,4890.6%EnergyARGXargenex$194,364,029$30,974,263 ▲19.0%266,0670.6%MedicalCAVACAVA Group$193,672,254$2,044,828 ▼-1.0%2,393,9710.6%Retail/WholesaleLSCCLattice Semiconductor$189,575,467$7,563,650 ▼-3.8%2,043,7200.6%Computer and TechnologyFFIVF5$188,049,455$28,841,572 ▲18.1%649,9480.6%Computer and TechnologyAKAMAkamai Technologies$185,949,041$185,949,041 ▲New Holding1,619,0600.6%Computer and TechnologyCCJCameco$182,714,877$32,422,682 ▼-15.1%1,682,3030.6%Basic MaterialsUNHUnitedHealth Group$182,178,239$24,077,099 ▼-11.7%673,2630.6%MedicalMDGLMadrigal Pharmaceuticals$178,251,481$7,172,062 ▼-3.9%340,5190.6%MedicalNUNU$176,285,412$92,424,492 ▼-34.4%12,267,6000.6%FinanceGMEDGlobus Medical$173,161,180$43,943,237 ▼-20.2%2,009,7630.6%MedicalCHRWC.H. Robinson Worldwide$172,988,144$100,332,353 ▲138.1%1,041,6580.6%TransportationEVERPURE INC$170,122,638$50,859,831 ▼-23.0%2,881,4810.6%CL ASNOWSnowflake$170,053,321$33,100,918 ▼-16.3%1,127,5250.6%Computer and TechnologyTALEN ENERGY CORP$167,664,065$14,105,178 ▼-7.8%525,2140.6%COMLOPEGrand Canyon Education$166,584,172$89,536,778 ▲116.2%979,7340.6%Consumer DiscretionaryEGEverest Group$165,440,357$25,538,425 ▼-13.4%506,1660.5%FinanceHALOHalozyme Therapeutics$163,253,764$44,143,518 ▲37.1%2,525,9750.5%MedicalMLMMartin Marietta Materials$160,351,723$1,288,621 ▲0.8%272,3920.5%ConstructionCOHRCoherent$159,156,915$48,814,708 ▼-23.5%668,1370.5%Business ServicesCWCurtiss-Wright$158,066,837$31,173,500 ▼-16.5%232,0690.5%AerospaceRRXRegal Rexnord$156,828,939$14,645,605 ▲10.3%837,4930.5%IndustrialsBWABorgWarner$156,489,204$156,489,204 ▲New Holding2,884,0620.5%Auto/Tires/TrucksCIENCiena$154,740,325$271,766,435 ▼-63.7%398,5790.5%Computer and TechnologyBRPThe Baldwin Insurance Group$149,071,154$16,440,103 ▼-9.9%6,794,4920.5%FinanceINSMInsmed$147,603,944$52,069,673 ▼-26.1%902,6660.5%MedicalNVTnVent Electric$145,942,617$16,711,190 ▼-10.3%1,233,8740.5%Computer and TechnologyCPRTCopart$145,887,008$6,362,647 ▼-4.2%4,394,1870.5%Business ServicesHQYHealthEquity$138,694,109$16,345,623 ▼-10.5%1,659,6160.5%MedicalCRSCarpenter Technology$138,305,658$26,275,221 ▼-16.0%350,8960.5%Basic MaterialsDCIDonaldson$137,094,670$7,852,427 ▼-5.4%1,615,3490.5%IndustrialsAPHAmphenol$136,133,786$136,133,786 ▲New Holding1,077,4340.4%Computer and TechnologyLECOLincoln Electric$133,220,687$18,671,286 ▼-12.3%534,8510.4%IndustrialsSTRLSterling Infrastructure$131,719,671$114,918,154 ▲684.0%323,4210.4%ConstructionMELIMercadoLibre$129,415,418$156,873,985 ▼-54.8%74,8490.4%Retail/WholesaleTECHBio-Techne$128,689,571$3,356,242 ▲2.7%2,462,4870.4%MedicalCLHClean Harbors$127,049,490$29,747,377 ▲30.6%443,0980.4%Business ServicesCMGChipotle Mexican Grill$125,180,643$19,130,200 ▲18.0%3,910,6730.4%Retail/WholesaleRSReliance$122,627,769$37,428,356 ▲43.9%403,4870.4%Basic MaterialsPOWIPower Integrations$121,890,662$121,890,662 ▲New Holding2,380,6770.4%Computer and TechnologyEXPEagle Materials$119,427,764$13,573,714 ▲12.8%630,3920.4%ConstructionDTDynatrace$119,410,306$488,062 ▲0.4%3,229,0510.4%Computer and TechnologyBSYBentley Systems$116,694,032$24,849,156 ▲27.1%3,322,7230.4%Computer and TechnologyGKOSGlaukos$115,607,354$3,563,438 ▼-3.0%1,073,8190.4%MedicalFHNFirst Horizon$115,122,174$6,325,664 ▼-5.2%5,058,0920.4%FinanceSNSharkNinja$113,671,366$17,255,028 ▼-13.2%1,073,3840.4%Retail/WholesaleVEEVVeeva Systems$113,006,470$41,789,163 ▼-27.0%643,3250.4%MedicalDOXIMITY INC$112,637,326$14,510,425 ▼-11.4%4,834,2200.4%CL ASYNASynaptics$111,100,530$111,100,530 ▲New Holding1,586,2440.4%Computer and TechnologyEYENational Vision$109,447,339$7,384,841 ▼-6.3%4,225,7660.4%Consumer StaplesPLNTPlanet Fitness$108,047,512$494,850 ▼-0.5%1,452,6420.4%Consumer DiscretionaryDIEBOLD NIXDORF INC$107,612,444$28,373,512 ▼-20.9%1,426,4640.4%COM SHSFRPTFreshpet$106,905,388$8,229,755 ▼-7.1%1,813,1850.4%Consumer StaplesTIGOMillicom International Cellular$105,336,264$95,955,649 ▲1,022.9%1,405,6080.3%Computer and TechnologyKRYSKrystal Biotech$105,182,221$7,966,072 ▲8.2%407,1780.3%MedicalGARRETT MOTION INC$104,708,204$5,389,040 ▼-4.9%5,762,6970.3%COMVRSKVerisk Analytics$103,888,884$28,074,082 ▲37.0%547,5040.3%Business ServicesLFUSLittelfuse$103,357,526$103,357,526 ▲New Holding304,5750.3%Computer and TechnologyAPPFAppFolio$101,514,716$787,522 ▲0.8%643,2310.3%Computer and TechnologyCWSTCasella Waste Systems$99,737,679$16,749,785 ▼-14.4%1,257,0920.3%Business ServicesCHDNChurchill Downs$98,219,134$4,673,316 ▼-4.5%1,093,3890.3%Consumer DiscretionaryNBHCNational Bank$96,915,557$96,915,557 ▲New Holding2,474,8610.3%FinanceNOVTNovanta$92,490,051$14,860,836 ▼-13.8%783,0840.3%Computer and TechnologyBIRKENSTOCK HOLDING PLC$92,276,654$92,276,654 ▲New Holding2,575,4020.3%COM SHSALHCAlignment Healthcare$91,881,499$51,262,906 ▲126.2%5,214,6140.3%MedicalPOOLPool$91,508,396$13,670,022 ▼-13.0%452,2730.3%Consumer DiscretionarySTEPStepStone Group$91,358,842$59,377,280 ▲185.7%1,914,4770.3%FinanceWMSAdvanced Drainage Systems$89,913,947$4,437,938 ▼-4.7%655,6840.3%ConstructionKMTKennametal$89,693,990$89,693,990 ▲New Holding2,482,5350.3%IndustrialsGHGuardant Health$87,854,400$87,854,400 ▲New Holding951,1140.3%MedicalONBOld National Bancorp$86,075,036$45,595,350 ▼-34.6%3,894,7980.3%FinanceFNFabrinet$85,962,142$18,510,831 ▼-17.7%164,8300.3%Computer and TechnologyShowing largest 100 holdings. 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