William Blair Investment Management
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William Blair Investment Management’s argenx ARGX Stock Holding History

William Blair Investment Management’s Portfolio ARGX Stock Details ARGX Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q2 		$245M Sell
264,617
-1,450
-0.5% -$1.2M 0.74% 21
2026
Q1 		$194M Buy
266,067
+42,401
+19% +$33.2M 0.64% 30
2025
Q4 		$188M Buy
+223,666
New +$191M 0.52% 45

Other funds holding ARGX

Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
T. Rowe Price Associates
T. Rowe Price Associates Baltimore, Maryland $999B AUM 46.22% 1-Year Est. Return
JT
Jupiter Topco New York $245B AUM
Capital World Investors
Capital World Investors Los Angeles, California $846B AUM 46.74% 1-Year Est. Return
Artisan Partners
Artisan Partners Milwaukee, Wisconsin $63.1B AUM 35.51% 1-Year Est. Return
ACA
Avoro Capital Advisors New York $11.1B AUM 207.82% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $580B AUM 38.23% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
RI
RTW Investments New York $11.7B AUM 174.13% 1-Year Est. Return
Morgan Stanley
Morgan Stanley New York $1.89T AUM 35.08% 1-Year Est. Return

William Blair Investment Management's ARGX Position: Q2 2026 in Review

William Blair Investment Management reduced its argenx (ARGX) stake by 0.54% in Q2 2026, selling an estimated $1.2M and leaving 264,617 shares worth $245M. The position accounts for 0.74% of the portfolio, ranked #21.

William Blair Investment Management first reported a position in ARGX in Q4 2025 and has held it in 3 quarters since. 506 funds tracked by Wall St. Rank hold ARGX as of Q2 2026.

  • William Blair Investment Management held 264,617 shares of argenx worth $245M as of Q2 2026.
  • William Blair Investment Management sold 1,450 argenx shares in Q2 2026, an estimated $1.2M.
  • argenx made up 0.74% of William Blair Investment Management's portfolio in Q2 2026, its #21 holding.
  • William Blair Investment Management first reported a position in argenx in Q4 2025 and has held it in 3 quarters since.
  • 506 funds tracked by Wall St. Rank held argenx as of Q2 2026.

Based on William Blair Investment Management's 13F filing for Q2 2026, filed 12 Aug 2026.