Arrowstreet Capital
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Arrowstreet Capital’s Prothena Corp PRTA Stock Holding History

Arrowstreet Capital’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
2026
Q1 		– Sell
-298,101
Closed -$2.85M – 2051
2025
Q4 		$2.85M Sell
298,101
-356,193
-54% -$3.63M ﹤0.01% 1296
2025
Q3 		$6.39M Buy
+654,294
New +$5.03M ﹤0.01% 1093
2020
Q3 		– Sell
-42,255
Closed -$442K – 2481
2020
Q2 		$442K Buy
+42,255
New +$470K ﹤0.01% 1997
2014
Q4 		– Sell
-168,562
Closed -$3.73M – 1319
2014
Q3 		$3.73M Buy
168,562
+141,187
+516% +$2.99M 0.02% 449
2014
Q2 		$617K Buy
+27,375
New +$685K ﹤0.01% 791
2014
Q1 		– Sell
-35,446
Closed -$940K – 1298
2013
Q4 		$940K Buy
+35,446
New +$889K 0.01% 838

Other funds holding PRTA

Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
RCMNY
Rubric Capital Management (New York) New York $10.9B AUM 70.31% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $3.37T AUM 44.26% 1-Year Est. Return
D.E. Shaw & Co
D.E. Shaw & Co New York $210B AUM 57.28% 1-Year Est. Return
ACM
ADAR1 Capital Management Austin, Texas $2.19B AUM 374.99% 1-Year Est. Return
Acadian Asset Management
Acadian Asset Management Boston, Massachusetts $84.2B AUM 55.88% 1-Year Est. Return
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM
Morgan Stanley
Morgan Stanley New York $1.89T AUM 35.08% 1-Year Est. Return
PAI
Palo Alto Investors Palo Alto, California $724M AUM 96.91% 1-Year Est. Return

Arrowstreet Capital's PRTA Position: Q1 2026 in Review

Arrowstreet Capital sold out of Prothena Corp (PRTA) in Q1 2026, closing a stake of 298,101 shares — an estimated $2.85M sold.

Arrowstreet Capital first reported a position in PRTA in Q4 2013 and held it in 6 quarters. The position peaked at $6.39M in Q3 2025. 185 funds tracked by Wall St. Rank hold PRTA as of Q1 2026.

  • Arrowstreet Capital reported no remaining Prothena Corp position as of Q1 2026 after selling out during the quarter.
  • Arrowstreet Capital sold 298,101 Prothena Corp shares in Q1 2026, an estimated $2.85M.
  • Arrowstreet Capital first reported a position in Prothena Corp in Q4 2013 and held it in 6 quarters.
  • Arrowstreet Capital's Prothena Corp position peaked at $6.39M in Q3 2025.
  • 185 funds tracked by Wall St. Rank held Prothena Corp as of Q1 2026.

Based on Arrowstreet Capital's 13F filing for Q1 2026, filed 14 May 2026.