1、MARKET CONCENTRATION:HOW BIG A WORRY?ISSUE 133|November 25,2024|5:00 PM EST&U&Global Macro ResearchInvestors should consider this report as only a single factor in making their investment decision.For Reg AC certification and other important disclosures,see the Disclosure Appendix,or go to Goldman S

2、achs Group,Inc.The t op 10 st ocks in t he S&P 500 account f or an out sized shar e of t he index s mar ket cap and of it s st ellar 2024 per f or mance.So,j ust how anomalous is t oday s equit y mar ket concent r at ion,and how wor r ying is it?GS David Kost in ar gues t hat t he unusually high con

3、cent r at ion war r ant s invest or concer n because hist or y suggest s t hat high concent r at ion is associat ed wit h lower long-r un r et ur ns.But Acadian s Owen Lamont t hinks wor r ies about concent r at ion ar e over blown,ar guing t hat concent r at ed mar ket s ar en t inher ent ly r iski

4、er and don t por t end f ut ur e poor per f or mance,t hough high valuat ion of t en does.At t he hear t of t he mat t er is whet her t he out per f or mance of t oday s dominant st ocks can per sist over t he longer t er m.Lamont and Kost in agr ee t his will likely pr ove dif ficult,and NYU St er

5、n s Thomas Philippon and Cr avat h s Noah Phillips opine on a key r isk t o sust ained out per f or mance:ant it r ust scr ut iny.So,GS st r at egist s advise st aying invest ed in US equit ies but r ecommend shif t ing some asset s t o equal-weight ed indices and diver sif ying acr oss st r at egie

6、s and r egions.“I NTERVI EWS WI TH:Owen Lamont,Senior Vice Pr esident and Por t f olio Manager at Acadian Asset Management LLC Noah Phillips,For mer FTC Commissioner,Co-Chair of t he Ant it r ust Pr act ice at Cr avat h Thomas Philippon,Pr of essor of Finance at New Yor k Univer sit y s St er n Scho