William Blair & Company
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William Blair & Company’s Korro Bio KRRO Stock Holding History

William Blair & Company’s Portfolio KRRO Stock Details KRRO Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2025
Q4 		– Sell
-9,750
Closed -$467K – 1908
2025
Q3 		$467K Buy
+9,750
New +$216K ﹤0.01% 1139
2025
Q2 		– Sell
-16,230
Closed -$283K – 1872
2025
Q1 		$283K Buy
16,230
+3,335
+26% +$98.9K ﹤0.01% 1282
2024
Q4 		$491K Buy
12,895
+695
+6% +$35.7K ﹤0.01% 1099
2024
Q3 		$408K Buy
+12,200
New +$513K ﹤0.01% 1182

Other funds holding KRRO

AVLSA
Atlas Venture Life Science Advisors Cambridge, Massachusetts $790M AUM 223.66% 1-Year Est. Return
NMC
NEA Management Company Timonium, Maryland $1.76B AUM 223.33% 1-Year Est. Return
LCM
Lynx1 Capital Management San Juan, Puerto Rico $633M AUM 173.22% 1-Year Est. Return
NCM
Nantahala Capital Management New Canaan, Connecticut $2.72B AUM 121.58% 1-Year Est. Return
Vanguard Group
Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
TCM
TCG Crossover Management Palo Alto, California $3.5B AUM 1,165.83% 1-Year Est. Return
SL
Siren LLC Greenwich, Connecticut $3.61B AUM 203.3% 1-Year Est. Return
Jane Street
Jane Street New York $777B AUM 61.18% 1-Year Est. Return
7IH
72 Investment Holdings Stamford, Connecticut $49.6M AUM 684.72% 1-Year Est. Return

William Blair & Company's KRRO Position: Q4 2025 in Review

William Blair & Company sold out of Korro Bio (KRRO) in Q4 2025, closing a stake of 9,750 shares — an estimated $467K sold.

William Blair & Company first reported a position in KRRO in Q3 2024 and held it in 4 quarters. The position peaked at $491K in Q4 2024. 83 funds tracked by Wall St. Rank hold KRRO as of Q4 2025.

  • William Blair & Company reported no remaining Korro Bio position as of Q4 2025 after selling out during the quarter.
  • William Blair & Company sold 9,750 Korro Bio shares in Q4 2025, an estimated $467K.
  • William Blair & Company first reported a position in Korro Bio in Q3 2024 and held it in 4 quarters.
  • William Blair & Company's Korro Bio position peaked at $491K in Q4 2024.
  • 83 funds tracked by Wall St. Rank held Korro Bio as of Q4 2025.

Based on William Blair & Company's 13F filing for Q4 2025, filed 17 Feb 2026.