Prothena Corp Public Ltd Co
PRTA- Exchange
- Nasdaq
- Industry
- Pharmaceutical Preparations
- SEC CIK
- 0001559053
In the last 90 days, Prothena Corp Public Ltd Co insiders filed 10 open-market purchases and 0 sales; 189 institutions reported holding it in 13F filings for Q2 2026, worth $462.7M in total; no superinvestor holds it.
Key figures
- Market capClose on Nov 11, 2026
- $448.3M
- Insider buysLast 90 days, $9.85M in total
- 10
- Insider sellsOpen market, last 90 days
- 0
- 13F holdersQ2 2026, +5 vs. previous quarter
- 189
- 13F valueReported value at the end of Q2 2026
- $462.7M
- Superinvestors holdingAt the end of Q2 2026
- 0
Price chart
Financials
See financial statementsFrom SEC filings, in USD.
- Revenue, FY2025
- $9.68M
- −92.8% year over year
- Net income, FY2025
- -$244.1M
- No comparable prior period
- Free cash flow, FY2025
- –
- No comparable prior period
- Revenue, Q3 FY2026
- $620.0K
- −74.3% year over year
Revenue flow, FY2025
Green is profit; orange is costs, expenses and taxes. Percentages are shares of revenue.
Net loss for FY2025: $244.1M (2520.6% of revenue).
Short interest
See short dataFrom FINRA, settlement date Oct 30, 2026.
- Short interest
- 7.91M
- Shares sold short
- Change
- −28.5K
- −0.4% vs. previous
- Days to cover
- 15.69
- At average daily volume
Superinvestors holding PRTA, Q2 2026
Go to the superinvestors tabNo superinvestor reported holding PRTA at the end of Q2 2026.
Latest insider trades
See all insider tradesOpen-market purchases and sales by Prothena Corp Public Ltd Co insiders from Form 4, newest first.
| Filed (ET) | Trade date | Filing delay | Insider | Transaction | Shares | Avg price | Value | Holding change | Flags |
|---|---|---|---|---|---|---|---|---|---|
| Nov 10, 2026 (view filing)2:45 PM ET | Nov 9 | 1 day | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +140.0K | $8.53 | +$1.19M | +16.7%977.0K after | |
| Oct 26, 2026 (view filing)4:20 PM ET | Oct 22-23 | 4 days | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +150.0K | $8.15 | +$1.22M | +14.5%1.19M after | 2 lots |
| Oct 15, 2026 (view filing)4:21 PM ET | Oct 13-14 | 2 days | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +110.0K | $8.36 | +$920.0K | +11.9%1.04M after | 2 lots |
| Oct 9, 2026 (view filing)9:43 AM ET | Oct 7-8 | 2 days | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +215.0K | $8.47 | +$1.82M | +68.5%529.0K after | 2 lots |
| Oct 6, 2026 (view filing)1:53 PM ET | Oct 2 | 4 days | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +100.0K | $8.57 | +$857.2K | +46.7%314.0K after | |
| Sep 30, 2026 (view filing)5:10 PM ET | Sep 29 | 1 day | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +162.0K | $8.68 | +$1.41M | +311.5%214.0K after | |
| Sep 29, 2026 (view filing)5:37 PM ET | Sep 28 | 1 day | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +103.5K | $8.60 | +$889.9K | +124.0%187.0K after | |
| Sep 21, 2026 (view filing)4:23 PM ET | Sep 18 | 3 days | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +100.0K | $8.43 | +$843.5K | +12.1%927.0K after | |
| Sep 3, 2026 (view filing)6:23 PM ET | Sep 2 | 1 day | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +27.0K | $9.47 | +$255.7K | +3.4%827.0K after | |
| Aug 21, 2026 (view filing)2:32 PM ET | Aug 20 | 1 day | Scully William P10% Owner | PPurchaseOrdinary Shares, par value $0.01 per share | +50.0K | $8.79 | +$439.4K | +6.7%800.0K after |
Top 10 13F holders, Q2 2026
See all 189 holdersThe largest institutional positions in Prothena Corp Public Ltd Co at the end of Q2 2026; share changes are against Q1 2026.
| Institution | Shares | Value | % of portfolio | Change in shares | Action |
|---|---|---|---|---|---|
| FMR LLC | 7,199,218 | $70.5M | 0.00% | −352,000−4.7% | Reduced |
| Rubric Capital Management LP | 5,000,000 | $49.0M | 0.45% | 00.0% | Unchanged |
| BlackRock, Inc. | 4,867,955 | $47.7M | 0.00% | +223,795+4.8% | Added |
| State Street Corp | 2,393,424 | $23.4M | 0.00% | +454,926+23.5% | Added |
| Acadian Asset Management LLC | 2,010,645 | $19.7M | 0.02% | +463,052+29.9% | Added |
| Vanguard Portfolio Management LLC | 1,651,293 | $16.2M | 0.00% | +205,314+14.2% | Added |
| D. E. Shaw & Co., Inc. | 1,611,457 | $15.8M | 0.01% | −151,890−8.6% | Reduced |
| ADAR1 Capital Management, LLC | 1,554,535 | $15.2M | 0.72% | −26,908−1.7% | Reduced |
| Two Sigma Investments, LP | 1,264,987 | $12.4M | 0.01% | +59,009+4.9% | Added |
| Palo Alto Investors LP | 1,143,155 | $11.2M | 1.55% | −65,413−5.4% | Reduced |
Holders of 5% or more of PRTA
See all 5 holders and filingsHolders whose latest Schedule 13D or 13G filing reports 5% or more of Prothena Corp Public Ltd Co.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| FMR LLC | 13G/A | 13.80%7.20M shares | – | Feb 8, 20216 filings | Aug 6, 2026 | SEC |
| Scully William P | 13G/A | 10.30%5.38M shares | +0.50 ppfrom 9.80% | Jun 27, 20229 filings | May 11, 2026 | SEC |
| Fennell Todd W. | 13G/A | 10.20%5.25M shares | +0.40 ppfrom 9.80% | Feb 14, 20248 filings | Aug 19, 2026 | SEC |
| Rubric Capital Management LP | 13G/A | 9.29%5.00M shares | +2.46 ppfrom 6.83% | Feb 13, 20262 filings | May 15, 2026 | SEC |
| BlackRock, Inc. | 13G/A | 6.90%3.59M shares | +1.20 ppfrom 5.70% | Oct 17, 20252 filings | Jul 29, 2026 | SEC |