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Rock Springs Capital Management’s Prothena Corp PRTA Stock Holding History

Rock Springs Capital Management’s Portfolio PRTA Stock Details PRTA Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2018
Q3 		– Sell
-85,000
Closed -$1.24M – 151
2018
Q2 		$1.24M Sell
85,000
-50,000
-37% -$988K 0.05% 143
2018
Q1 		$4.96M Buy
135,000
+110,000
+440% +$4M 0.21% 120
2017
Q4 		$937K Buy
+25,000
New +$1.27M 0.04% 141

Other funds holding PRTA

Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
RCMNY
Rubric Capital Management (New York) New York $9.44B AUM 68.42% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return
Vanguard Group
Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return
D.E. Shaw & Co
D.E. Shaw & Co New York $166B AUM 43.98% 1-Year Est. Return
AC
Armistice Capital New York $5.62B AUM 36.06% 1-Year Est. Return
ACM
ADAR1 Capital Management Austin, Texas $1.7B AUM 340.85% 1-Year Est. Return
Acadian Asset Management
Acadian Asset Management Boston, Massachusetts $70.5B AUM 36% 1-Year Est. Return
PAI
Palo Alto Investors Palo Alto, California $654M AUM 77.8% 1-Year Est. Return

Rock Springs Capital Management's PRTA Position: Q4 2025 in Review

Rock Springs Capital Management sold out of Prothena Corp (PRTA) in Q4 2025, closing a stake of 25,398 shares — an estimated $248K sold.

Rock Springs Capital Management first reported a position in PRTA in Q1 2014 and held it in 40 quarters. The position peaked at $51.4M in Q2 2023. 181 funds tracked by Wall St. Rank hold PRTA as of Q4 2025.

  • Rock Springs Capital Management reported no remaining Prothena Corp position as of Q4 2025 after selling out during the quarter.
  • Rock Springs Capital Management sold 25,398 Prothena Corp shares in Q4 2025, an estimated $248K.
  • Rock Springs Capital Management first reported a position in Prothena Corp in Q1 2014 and held it in 40 quarters.
  • Rock Springs Capital Management's Prothena Corp position peaked at $51.4M in Q2 2023.
  • 181 funds tracked by Wall St. Rank held Prothena Corp as of Q4 2025.

Based on Rock Springs Capital Management's 13F filing for Q4 2025, filed 17 Feb 2026.