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
2025 Q4	–	Sell	-25,398	Closed	-$248K	–	110
2025 Q3	$248K	Sell	25,398 -467,203	-95%	-$3.59M	0.01%	90
2025 Q2	$2.99M	Hold	492,601	–	–	0.19%	73
2025 Q1	$6.1M	Sell	492,601 -152,000	-24%	-$2.15M	0.35%	60
2024 Q4	$8.93M	Buy	644,601 +19,553	+3%	+$308K	0.34%	66
2024 Q3	$10.5M	Hold	625,048	–	–	0.34%	67
2024 Q2	$12.9M	Hold	625,048	–	–	0.39%	62
2024 Q1	$15.5M	Hold	625,048	–	–	0.39%	65
2023 Q4	$22.7M	Buy	625,048 +10,750	+2%	+$414K	0.56%	52
2023 Q3	$29.6M	Sell	614,298 -139,164	-18%	-$8.27M	0.79%	40
2023 Q2	$51.4M	Hold	753,462	–	–	1.22%	27
2023 Q1	$36.5M	Hold	753,462	–	–	0.87%	43
2022 Q4	$45.4M	Buy	753,462 +75,000	+11%	+$4.39M	1.09%	34
2022 Q3	$41.1M	Hold	678,462	–	–	1.06%	32
2022 Q2	$18.4M	Buy	678,462 +14,932	+2%	+$437K	0.54%	56
2022 Q1	$24.3M	Buy	663,530 +15,800	+2%	+$570K	0.61%	55
2021 Q4	$32M	Sell	647,730 -62,700	-9%	-$3.48M	0.74%	47
2021 Q3	$50.6M	Sell	710,430 -239,661	-25%	-$14.9M	1.06%	30
2021 Q2	$48.8M	Sell	950,091 -206,809	-18%	-$6.45M	0.97%	32
2021 Q1	$29.1M	Buy	1,156,900 +15,800	+1%	+$297K	0.63%	55
2020 Q4	$13.7M	Buy	1,141,100 +115,893	+11%	+$1.37M	0.29%	100
2020 Q3	$10.2M	Buy	1,025,207 +35,989	+4%	+$433K	0.26%	101
2020 Q2	$10.3M	Buy	989,218 +489,218	+98%	+$5.44M	0.28%	103
2020 Q1	$5.35M	Buy	+500,000	New	+$6.06M	0.22%	94
2018 Q2	–	Sell	-318,500	Closed	-$6.29M	–	151
2018 Q1	$11.7M	Buy	318,500 +8,500	+3%	+$309K	0.5%	71
2017 Q4	$11.6M	Buy	310,000 +500	+0.2%	+$25.5K	0.53%	66
2017 Q3	$20M	Hold	309,500	–	–	0.92%	36
2017 Q2	$16.8M	Hold	309,500	–	–	0.85%	43
2017 Q1	$17.3M	Hold	309,500	–	–	1%	34
2016 Q4	$15.2M	Buy	309,500 +1,500	+0.5%	+$82.8K	1.02%	32
2016 Q3	$18.5M	Hold	308,000	–	–	1.16%	28
2016 Q2	$10.8M	Hold	308,000	–	–	0.8%	40
2016 Q1	$12.7M	Buy	308,000 +60,000	+24%	+$2.35M	1.06%	28
2015 Q4	$16.9M	Hold	248,000	–	–	1.28%	23
2015 Q3	$11.2M	Sell	248,000 -2,000	-0.8%	-$116K	0.91%	37
2015 Q2	$13.2M	Buy	250,000 +12,500	+5%	+$493K	0.96%	33
2015 Q1	$9.06M	Buy	237,500 +35,000	+17%	+$898K	0.85%	41
2014 Q4	$4.2M	Hold	202,500	–	–	0.49%	62
2014 Q3	$4.49M	Buy	202,500 +52,500	+35%	+$1.11M	0.69%	45
2014 Q2	$3.38M	Buy	150,000 +85,000	+131%	+$2.13M	0.61%	60
2014 Q1	$2.49M	Buy	+65,000	New	+$2.1M	0.57%	55

Other funds holding PRTA

Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return

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 Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return

Vanguard Group Malvern, Pennsylvania $6.9T AUM 27.45% 1-Year Est. Return

D.E. Shaw & Co New York $166B AUM 43.98% 1-Year Est. Return

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 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.