Prothena Corp Public (PRTA) Latest Stock Analysis Report – Oct 15, 2026, 4:00 PM ET
Updated Oct 15, 2026, 4:00 PM ET
- Closed at $8.50, +1.55% vs the prior close of $8.37.
- Volume 358.40K shares, 0.8x its 50-day average.
- New SEC filings: 4 (Oct 15, 2026).
- No new insider buys or sales reported since the prior session.
PRTA rises 1.6% to $8.50. Closed at $8.50, +1.55% vs the prior close of $8.37. Day range $8.44–$8.65, opened at $8.54.
PRTA daily analysis — what happened
A plain-English, data-only note written after every US trading day. Newest first; older days stay archived below.
Oct 15, 2026 — PRTA rises 1.6% to $8.50
- Closed at $8.50, +1.55% vs the prior close of $8.37. Day range $8.44–$8.65, opened at $8.54.
- Volume was 358.40K shares, 0.8x its 50-day average of 465.85K.
- Price is -4.2% vs its 50-day average ($8.87) and -8.3% vs its 200-day average ($9.27).
- 52-week range $7.73–$11.80; today's close sits at 19% of that range, 28.0% below the 52-week high.
Oct 14, 2026 — PRTA ends flat (+0.1%) to $8.37
- Closed at $8.37, +0.12% vs the prior close of $8.36. Day range $8.19–$8.56, opened at $8.28.
- Volume was 619.10K shares, 1.3x its 50-day average of 460.06K.
- Price is -5.6% vs its 50-day average ($8.87) and -9.8% vs its 200-day average ($9.28).
- 52-week range $7.73–$11.80; today's close sits at 16% of that range, 29.1% below the 52-week high.
Oct 13, 2026 — PRTA dips 0.8% to $8.36
- Closed at $8.36, -0.83% vs the prior close of $8.43. Day range $8.20–$8.55, opened at $8.45.
- Volume was 573.30K shares, 1.2x its 50-day average of 459.92K.
- Price is -5.8% vs its 50-day average ($8.87) and -9.9% vs its 200-day average ($9.28).
- 52-week range $7.73–$11.80; today's close sits at 15% of that range, 29.2% below the 52-week high.
Oct 12, 2026 — PRTA slides 4.6% to $8.43
- Closed at $8.43, -4.64% vs the prior close of $8.84. Day range $8.40–$8.81, opened at $8.81.
- Volume was 489.80K shares, 1.1x its 50-day average of 461.03K.
- Price is -5.0% vs its 50-day average ($8.87) and -9.3% vs its 200-day average ($9.29).
- 52-week range $7.73–$11.80; today's close sits at 17% of that range, 28.6% below the 52-week high.
Oct 9, 2026 — PRTA rises 2.7% to $8.84 on 2.1x normal volume
- Closed at $8.84, +2.67% vs the prior close of $8.61. Day range $8.50–$9.31, opened at $8.57.
- Volume was 931.60K shares, 2.1x its 50-day average of 452.44K — unusually heavy trading.
- Price is -0.3% vs its 50-day average ($8.87) and -4.9% vs its 200-day average ($9.30).
- 52-week range $7.73–$11.80; today's close sits at 27% of that range, 25.1% below the 52-week high.
- That makes 3 straight gains.
Oct 8, 2026 — PRTA rises 1.5% to $8.61
- Closed at $8.61, +1.53% vs the prior close of $8.48. Day range $8.36–$8.81, opened at $8.43.
- Volume was 642.40K shares, 1.4x its 50-day average of 452.42K.
- Price is -2.8% vs its 50-day average ($8.86) and -7.4% vs its 200-day average ($9.30).
- 52-week range $7.73–$11.80; today's close sits at 22% of that range, 27.0% below the 52-week high.
Oct 7, 2026 — PRTA jumps 5.7% to $8.48
- Closed at $8.48, +5.74% vs the prior close of $8.02. Day range $7.88–$8.63, opened at $7.93.
- Volume was 690.40K shares, 1.5x its 50-day average of 454.66K.
- Price is -4.2% vs its 50-day average ($8.86) and -8.8% vs its 200-day average ($9.30).
- 52-week range $7.73–$11.80; today's close sits at 18% of that range, 28.1% below the 52-week high.
Oct 6, 2026 — PRTA slides 3.0% to $8.02, a 3-month low, 3 down days in a row
- Closed at $8.02, -3.02% vs the prior close of $8.27. Day range $7.80–$8.28, opened at $8.28.
- Volume was 508.30K shares, 1.1x its 50-day average of 458.58K.
- Price is -9.5% vs its 50-day average ($8.86) and -13.8% vs its 200-day average ($9.31).
- 52-week range $7.73–$11.80; today's close sits at 7% of that range, 32.0% below the 52-week high.
- That makes 3 straight losses.
Oct 5, 2026 — PRTA dips 1.1% to $8.27
- Closed at $8.27, -1.08% vs the prior close of $8.36. Day range $7.91–$8.37, opened at $8.34.
- Volume was 714.50K shares, 1.6x its 50-day average of 455.83K.
- Price is -6.8% vs its 50-day average ($8.87) and -11.2% vs its 200-day average ($9.31).
- 52-week range $7.73–$11.80; today's close sits at 13% of that range, 29.9% below the 52-week high.
Oct 2, 2026 — PRTA dips 2.1% to $8.36
- Closed at $8.36, -2.11% vs the prior close of $8.54. Day range $8.35–$8.62, opened at $8.62.
- Volume was 675.80K shares, 1.5x its 50-day average of 452.96K.
- Price is -5.9% vs its 50-day average ($8.88) and -10.3% vs its 200-day average ($9.32).
- 52-week range $7.73–$11.80; today's close sits at 15% of that range, 29.2% below the 52-week high.
- SEC filings that day: 8-K.
PRTA latest news & SEC filings
Every SEC filing by or about PRTA in the last 120 days, explained in plain English. Updated daily, with a same-day refresh for new filings.
Oct 15, 2026 · Form 4 — Insider trade
Insider trade report (Form 4) — a director, officer or 10%+ owner changed their holdings
- Scully William P bought 100,000 shares at $8.35 (≈$835.48K) on Oct 13, 2026; now holds 1,027,000
- Scully William P bought 10,000 shares at $8.46 (≈$84.57K) on Oct 14, 2026; now holds 1,037,000
Open-market purchases (P) and sales (S) are shown in colour; awards, exercises and tax withholding are routine pay-related moves. Many sales are pre-planned under 10b5-1 plans.
Oct 9, 2026 · Form 4 — Insider trade
Insider trade report (Form 4) — a director, officer or 10%+ owner changed their holdings
- Scully William P bought 125,000 shares at $8.40 (≈$1.05M) on Oct 7, 2026; now holds 439,000
- Scully William P bought 90,000 shares at $8.57 (≈$770.90K) on Oct 8, 2026; now holds 529,000
Open-market purchases (P) and sales (S) are shown in colour; awards, exercises and tax withholding are routine pay-related moves. Many sales are pre-planned under 10b5-1 plans.
Oct 6, 2026 · Form 4 — Insider trade
Insider trade report (Form 4) — a director, officer or 10%+ owner changed their holdings
- Scully William P bought 100,000 shares at $8.57 (≈$857.24K) on Oct 2, 2026; now holds 314,000
Open-market purchases (P) and sales (S) are shown in colour; awards, exercises and tax withholding are routine pay-related moves. Many sales are pre-planned under 10b5-1 plans.
Oct 2, 2026 · Form 8-K — Major event / current report
Current report — a filing companies must make within 4 business days of a major event
- Item 5.02 — Change in directors or officers (appointment, departure or pay).
Sep 30, 2026 · Form 4 — Insider trade
Insider trade report (Form 4) — a director, officer or 10%+ owner changed their holdings
- Scully William P bought 162,000 shares at $8.68 (≈$1.41M) on Sep 29, 2026; now holds 214,000
Open-market purchases (P) and sales (S) are shown in colour; awards, exercises and tax withholding are routine pay-related moves. Many sales are pre-planned under 10b5-1 plans.
Sep 29, 2026 · Form 4 — Insider trade
Insider trade report (Form 4) — a director, officer or 10%+ owner changed their holdings
- Scully William P bought 103,500 shares at $8.60 (≈$889.87K) on Sep 28, 2026; now holds 187,000
Open-market purchases (P) and sales (S) are shown in colour; awards, exercises and tax withholding are routine pay-related moves. Many sales are pre-planned under 10b5-1 plans.
Sep 21, 2026 · Form 4 — Insider trade
Insider trade report (Form 4) — a director, officer or 10%+ owner changed their holdings
- Scully William P bought 100,000 shares at $8.43 (≈$843.46K) on Sep 18, 2026; now holds 927,000
Open-market purchases (P) and sales (S) are shown in colour; awards, exercises and tax withholding are routine pay-related moves. Many sales are pre-planned under 10b5-1 plans.
Aug 19, 2026 · Form SCHEDULE 13G/A — Update to a passive 5%+ stake (13G)
Update to a passive 5%+ stake (13G)
Filed by an outside investor (not the company). It reports a holding of more than 5% of a share class; percentage and holder name are in the filing.
Aug 14, 2026 · Form SCHEDULE 13G/A — Update to a passive 5%+ stake (13G)
Update to a passive 5%+ stake (13G)
Filed by an outside investor (not the company). It reports a holding of more than 5% of a share class; percentage and holder name are in the filing.
Aug 6, 2026 · Form 10-Q — Quarterly report
Quarterly report (unaudited financial statements for the quarter)
Quarter ended Jun 30, 2026:
- Revenue: $1.01M (prior year $4.42M) (-77.1% vs Jun 30, 2025)
- Net income: -$18.58M (prior year -$125.77M) (loss narrowed vs Jun 30, 2025)
- Diluted EPS: -$0.36 (prior year -$2.34) (loss narrowed vs Jun 30, 2025)
Aug 6, 2026 · Form 8-K — Major event / current report
Current report — a filing companies must make within 4 business days of a major event
- Item 2.02 — Reported results of operations (earnings release).
This is a results-day filing: the earnings press release is attached as an exhibit.
Aug 6, 2026 · Form SCHEDULE 13G/A — Update to a passive 5%+ stake (13G)
Update to a passive 5%+ stake (13G)
Filed by an outside investor (not the company). It reports a holding of more than 5% of a share class; percentage and holder name are in the filing.
Jul 29, 2026 · Form SCHEDULE 13G/A — Update to a passive 5%+ stake (13G)
Update to a passive 5%+ stake (13G)
Filed by an outside investor (not the company). It reports a holding of more than 5% of a share class; percentage and holder name are in the filing.
Things to know before you trade PRTA
- Last results release: Aug 6, 2026 (8-K Item 2.02). Previous ones: May 7, 2026, Feb 19, 2026, Nov 6, 2025. Based on that rhythm, the next report is likely around Nov 5, 2026 — an estimate, not a confirmed date.
- How much it moves: over the last 20 sessions the average daily move was 2.57% (largest 5.7%).
- Liquidity: about 614.50K shares (≈$5.22M) trade per day on average.
- 52-week position: $8.50 vs a range of $7.73–$11.80 (19% of the range).
- Dividends: no cash dividends in the last 2 years.
- Splits: none in the last 2 years.
- Insider trades (Form 4, last 12 months, recent 25 shown): 12 open-market buys, 2 sales; latest: William P Scully bought 162,000 shares on Sep 29, 2026.
- Latest filings: 8-K Oct 2, 2026; 10-Q Aug 6, 2026; 8-K Aug 6, 2026.
- Share count: 51.34M shares outstanding (Jul 30, 2026), -4.6% vs a year earlier — the company has been reducing its share count.
- Listing: Nasdaq · industry: Pharmaceutical Preparations.
PRTA market data (last 20 sessions)
| Date | Open | High | Low | Close | Volume |
|---|---|---|---|---|---|
| Oct 15, 2026 | 8.54 | 8.65 | 8.44 | 8.50 | 358.40K |
| Oct 14, 2026 | 8.28 | 8.56 | 8.19 | 8.37 | 619.10K |
| Oct 13, 2026 | 8.45 | 8.55 | 8.20 | 8.36 | 573.30K |
| Oct 12, 2026 | 8.81 | 8.81 | 8.40 | 8.43 | 489.80K |
| Oct 9, 2026 | 8.57 | 9.31 | 8.50 | 8.84 | 931.60K |
| Oct 8, 2026 | 8.43 | 8.81 | 8.36 | 8.61 | 642.40K |
| Oct 7, 2026 | 7.93 | 8.63 | 7.88 | 8.48 | 690.40K |
| Oct 6, 2026 | 8.28 | 8.28 | 7.80 | 8.02 | 508.30K |
| Oct 5, 2026 | 8.34 | 8.37 | 7.91 | 8.27 | 714.50K |
| Oct 2, 2026 | 8.62 | 8.62 | 8.35 | 8.36 | 675.80K |
| Oct 1, 2026 | 8.54 | 8.58 | 8.35 | 8.54 | 457.10K |
| Sep 30, 2026 | 8.98 | 8.99 | 8.36 | 8.38 | 634.80K |
| Sep 29, 2026 | 8.66 | 8.80 | 8.59 | 8.78 | 602.30K |
| Sep 28, 2026 | 8.25 | 8.86 | 8.07 | 8.72 | 488.90K |
| Sep 25, 2026 | 8.38 | 8.52 | 8.19 | 8.29 | 481.00K |
| Sep 24, 2026 | 8.63 | 8.73 | 8.28 | 8.32 | 426.10K |
| Sep 23, 2026 | 8.94 | 8.97 | 8.66 | 8.68 | 357.80K |
| Sep 22, 2026 | 8.72 | 9.09 | 8.70 | 8.99 | 445.50K |
| Sep 21, 2026 | 8.59 | 8.80 | 8.46 | 8.51 | 361.90K |
| Sep 18, 2026 | 8.41 | 8.60 | 8.25 | 8.58 | 1.83M |
About Prothena Corp Public
Prothena Corp Public (PRTA) is listed on the Nasdaq and classified by the SEC under “Pharmaceutical Preparations”. Its business address is in DUBLIN 2, Ireland. State of incorporation: Ireland. Fiscal year ends December 31. SEC CIK 1559053.
PRTA board of directors & executives
From SEC Form 3/4/5 insider filings made in the last 12 months (date = latest filing).
Directors
| Name | Role | Latest filing |
|---|---|---|
| Richard T Collier | Director | May 15, 2026 |
| Shane Cooke | Director | May 15, 2026 |
| William H. Jr. Dunn | Director | May 15, 2026 |
| Lars Ekman | Director | May 15, 2026 |
| Gene G. Kinney | President and CEO | Jul 30, 2026 |
| Dennis J. Selkoe | Director | May 15, 2026 |
| Daniel G Welch | Director | May 15, 2026 |
Executive officers
| Name | Title | Latest filing |
|---|---|---|
| Michael John Isaacs | General Counsel & Company Sec. | Jul 30, 2026 |
| Anne Evans Kingston | Chief Strategy Officer | Jul 30, 2026 |
| Gene G. Kinney | President and CEO | Jul 30, 2026 |
| Michael J Malecek | Chief Legal Officer | Mar 5, 2026 |
| Tran Nguyen | Chief Strategy Officer and CFO | Jul 30, 2026 |
| Brandon S. Smith | Chief Operating Officer | Jul 30, 2026 |
| Chad J. Swanson | Chief Development Officer | Jul 30, 2026 |
| Karin L Walker | Chief Accounting Officer | Jul 30, 2026 |
| Wagner M. Zago | Chief Scientific Officer | Jul 30, 2026 |
Recent insider buys & sales
| Date | Insider | Type | Shares | Price |
|---|---|---|---|---|
| Sep 29, 2026 | William P Scully | Buy | 162,000 | $8.68 |
| Sep 28, 2026 | William P Scully | Buy | 103,500 | $8.60 |
| Sep 18, 2026 | William P Scully | Buy | 100,000 | $8.43 |
| Sep 2, 2026 | William P Scully | Buy | 27,000 | $9.47 |
| Aug 20, 2026 | William P Scully | Buy | 50,000 | $8.79 |
| Aug 7, 2026 | William P Scully | Buy | 3,500 | $8.62 |
| Aug 7, 2026 | William P Scully | Buy | 34,000 | $8.62 |
| Jul 29, 2026 | Michael John Isaacs | Sale | 8,386 | $8.47 |
| Jul 29, 2026 | Anne Evans Kingston | Sale | 7,662 | $8.47 |
| Jun 16, 2026 | William P Scully | Buy | 20,000 | $7.90 |
| Jun 11, 2026 | William P Scully | Buy | 125,000 | $8.17 |
| Jun 4, 2026 | William P Scully | Buy | 50,000 | $9.31 |
| Jun 2, 2026 | William P Scully | Buy | 50,000 | $9.43 |
| May 22, 2026 | William P Scully | Buy | 100,000 | $9.81 |
PRTA financials (annual, from XBRL filings)
| Fiscal year end | Revenue | Net income | Diluted EPS | Operating cash flow |
|---|---|---|---|---|
| Dec 31, 2025 | $9.68M | $-244.09M | -4.53 | $-163.58M |
| Dec 31, 2024 | $135.16M | $-122.31M | -2.27 | $-150.05M |
| Dec 31, 2023 | $91.37M | $-147.03M | -2.76 | $-133.91M |
| Dec 31, 2022 | $53.91M | $-116.95M | -2.47 | $-108.82M |
| Dec 31, 2021 | $200.58M | $66.97M | 1.38 | $92.61M |
Latest balance sheet: total assets $302.58M, total liabilities $15.69M, cash $288.19M (as of Jun 30, 2026).
PRTA earnings / results-day log
| Date | Filing | Close that day |
|---|---|---|
| Aug 6, 2026 | 8-K Item 2.02 (results) | $8.58 |
| May 7, 2026 | 8-K Item 2.02 (results) | $10.52 |
| Feb 19, 2026 | 8-K Item 2.02 (results) | $9.03 |
| Nov 6, 2025 | 8-K Item 2.02 (results) | $10.08 |
| Aug 4, 2025 | 8-K Item 2.02 (results) | $6.94 |
| May 8, 2025 | 8-K Item 2.02 (results) | $7.10 |
| Feb 20, 2025 | 8-K Item 2.02 (results) | $15.25 |
| Nov 12, 2024 | 8-K Item 2.02 (results) | $17.36 |
| Aug 8, 2024 | 8-K Item 2.02 (results) | — |
| May 8, 2024 | 8-K Item 2.02 (results) | — |
| Feb 15, 2024 | 8-K Item 2.02 (results) | — |
| Jan 8, 2024 | 8-K Item 2.02 (results) | — |
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Information only, not investment advice. BuyMeWhiskey is not a registered investment adviser or broker-dealer; nothing here is a recommendation to buy, sell or hold any security, and there are no price targets. Data comes from SEC EDGAR filings and public end-of-day market data and may be delayed or contain errors. Verify with the company's filings before making decisions. Prices: end-of-day data as of Oct 15, 2026, 4:00 PM ET. Filings: SEC EDGAR. Updated after every US trading day.