Janus Henderson Group
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Janus Henderson Group’s Prothena Corp PRTA Stock Holding History

Janus Henderson Group’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
2025
Q3 		– Sell
-18,047
Closed -$110K – 2453
2025
Q2 		$110K Hold
18,047
– – ﹤0.01% 2392
2025
Q1 		$237K Hold
18,047
– – ﹤0.01% 2304
2024
Q4 		$249K Hold
18,047
– – ﹤0.01% 2335
2024
Q3 		$301K Sell
18,047
-1,008,511
-98% -$21.7M ﹤0.01% 2272
2024
Q2 		$21.2M Sell
1,026,558
-283,032
-22% -$6.12M 0.01% 555
2024
Q1 		$32.4M Sell
1,309,590
-726,394
-36% -$21.6M 0.02% 469
2023
Q4 		$74M Buy
2,035,984
+209,375
+11% +$8.06M 0.04% 301
2023
Q3 		$88.1M Buy
1,826,609
+154,078
+9% +$9.15M 0.06% 258
2023
Q2 		$114M Buy
1,672,531
+76,228
+5% +$4.92M 0.07% 238
2023
Q1 		$77.4M Buy
1,596,303
+163,980
+11% +$8.66M 0.05% 299
2022
Q4 		$86.3M Buy
1,432,323
+1,126,427
+368% +$66M 0.06% 265
2022
Q3 		$18.6M Buy
305,896
+122,856
+67% +$3.88M 0.01% 695
2022
Q2 		$4.97M Buy
183,040
+177,545
+3,231% +$5.19M ﹤0.01% 845
2022
Q1 		$201K Hold
5,495
– – ﹤0.01% 2440
2021
Q4 		$272K Buy
+5,495
New +$305K ﹤0.01% 2243

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
Vanguard Group
Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return
AC
Armistice Capital New York $5.62B AUM 36.06% 1-Year Est. Return
RCMNY
Rubric Capital Management (New York) New York $9.44B AUM 68.42% 1-Year Est. Return
ACM
ADAR1 Capital Management Austin, Texas $1.7B AUM 340.85% 1-Year Est. Return
PAI
Palo Alto Investors Palo Alto, California $654M AUM 77.8% 1-Year Est. Return
D.E. Shaw & Co
D.E. Shaw & Co New York $166B AUM 43.98% 1-Year Est. Return
Acadian Asset Management
Acadian Asset Management Boston, Massachusetts $70.5B AUM 36% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return

Janus Henderson Group's PRTA Position: Q3 2025 in Review

Janus Henderson Group sold out of Prothena Corp (PRTA) in Q3 2025, closing a stake of 18,047 shares — an estimated $110K sold.

Janus Henderson Group first reported a position in PRTA in Q4 2021 and held it in 15 quarters. The position peaked at $114M in Q2 2023. 187 funds tracked by Wall St. Rank hold PRTA as of Q3 2025.

  • Janus Henderson Group reported no remaining Prothena Corp position as of Q3 2025 after selling out during the quarter.
  • Janus Henderson Group sold 18,047 Prothena Corp shares in Q3 2025, an estimated $110K.
  • Janus Henderson Group first reported a position in Prothena Corp in Q4 2021 and held it in 15 quarters.
  • Janus Henderson Group's Prothena Corp position peaked at $114M in Q2 2023.
  • 187 funds tracked by Wall St. Rank held Prothena Corp as of Q3 2025.

Based on Janus Henderson Group's 13F filing for Q3 2025, filed 14 Nov 2025.