Prothena Corporation plc - Ordinary Shares (PRTA)
PRTA moved a median of -0.04% 30 minutes after news, and 0.00% by the close. How PRTA actually reacts to news — the realized, point-in-time move the market made, measured across 256 labeled events over the last three years with zero look-ahead.
PRTA’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | +0.34% | 55% | 254 |
| 30-min | -0.04% | 49% | 256 |
| 60-min | +0.22% | 54% | 256 |
| to close | 0.00% | 50% | 254 |
| Middle 50% of PRTA reactions | -1.09% to +1.76% |
|---|---|
| Median reaction (30-min) | -0.04% |
| Measured reactions | 256 |
Half of all Prothena Corporation plc - Ordinary Shares news events land between -1.09% and +1.76% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
How PRTA reacts, by analyst action.
| Event | Events | Median 30-min | % positive | Median to close |
|---|---|---|---|---|
| Analyst upgrades | 12 | -0.90% | 25% | -1.58% |
| Analyst downgrades | 21 | -0.19% | 48% | -2.37% |
| Rating reiterations | 76 | +0.31% | 63% | -0.80% |
| Price-target cuts | 21 | +0.56% | 76% | -0.42% |
Last 3 years, pulled 2026-09-21. Reaction = percent move vs. the price at the news timestamp. Counts and medians only. The same measurement runs across every name in the dataset. 2 further classes were observed with fewer than 10 measured events and are not published. See how PRTA ranks against every other measured name →
That’s how PRTA usually reacts — get an email when it moves on news →Email me when PRTA moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to PRTA's baseline. Nothing else.
Recent PRTA events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Form 8-K PROTHENA CORP PUBLIC For: Oct 02 | SEC filing · Form 8-K | SEC EDGAR | -1.69% | -0.36% | |
| Prothena to Participate in the H.C. Wainwright 28th Annual Global Investment Conference | Press release | Business Wire | -1.14% | -2.49% | |
| Form 10-Q PROTHENA CORP PUBLIC For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | -2.40% | +2.58% | |
| Form 8-K PROTHENA CORP PUBLIC For: Aug 06 | SEC filing · Form 8-K | SEC EDGAR | -2.40% | +2.58% | |
| Prothena Reports Second Quarter 2026 Financial Results and Business Highlights | Press release | Business Wire | -2.40% | +2.58% | |
| Prothena to Report Second Quarter 2026 Financial Results on August 6 | Press release | Business Wire | +0.47% | -3.45% | |
| Form 8-K PROTHENA CORP PUBLIC For: May 14 | SEC filing · Form 8-K | SEC EDGAR | +3.67% | -0.72% | |
| Form 10-Q PROTHENA CORP PUBLIC For: Mar 31 | SEC filing · Form 10-Q | SEC EDGAR | +0.86% | -2.46% | |
| Form 8-K PROTHENA CORP PUBLIC For: May 07 | SEC filing · Form 8-K | SEC EDGAR | +0.86% | -2.46% | |
| Prothena Reports First Quarter 2026 Financial Results and Business Highlights | Press release | Business Wire | +0.86% | -2.46% | |
| Prothena to Report First Quarter 2026 Financial Results on May 7 | Press release | Business Wire | -0.81% | -3.62% | |
| Prothena Announces Novo Nordisk Obtains Fast Track Designation from the U.S. FDA for Coramitug (PRX004) in ATTR Amyloidosis with Cardiomyopathy | Press release | Business Wire | +2.95% | +6.18% | |
| Prothena Announces Leadership Team Updates | Press release | Business Wire | +0.00% | -1.72% | |
| Form ARS PROTHENA CORP PUBLIC For: Dec 31 | SEC filing · Form ARS | SEC EDGAR | +2.06% | +0.11% | |
| Form DEF 14A PROTHENA CORP PUBLIC For: May 14 | SEC filing · Form DEF | SEC EDGAR | +2.06% | +0.11% | |
| Form DEFA14A PROTHENA CORP PUBLIC | SEC filing · Form DEFA14A | SEC EDGAR | +2.06% | +0.11% | |
| Prothena Partners Present Data Supporting Next Generation Treatments for Parkinson’s and Alzheimer’s Disease at AD/PD™ 2026 | Press release | Business Wire | -0.74% | -0.11% | |
| Prothena Announces Achievement of $50 Million Clinical Milestone Payment from Novo Nordisk Related to Ongoing Phase 3 Clinical Trial for Coramitug (Formerly PRX004) in ATTR Amyloidosis with Cardiomyopathy | Press release | Business Wire | -1.08% | -4.31% | |
| Form EFFECT PROTHENA CORP PUBLIC | SEC filing · Form EFFECT | SEC EDGAR | +0.11% | +2.97% | |
| Form 10-K PROTHENA CORP PUBLIC For: Dec 31 | SEC filing · Form 10-K | SEC EDGAR | +0.00% | +3.41% | |
| Form 8-K PROTHENA CORP PUBLIC For: Feb 27 | SEC filing · Form 8-K | SEC EDGAR | +0.00% | +3.41% | |
| Form POS AM PROTHENA CORP PUBLIC | SEC filing · Form POS | SEC EDGAR | +0.00% | +3.41% | |
| Form POSASR PROTHENA CORP PUBLIC | SEC filing · Form POSASR | SEC EDGAR | +0.00% | +3.41% | |
| Prothena Announces up to $100 Million Share Repurchase Plan | Press release | Business Wire | +0.00% | +3.41% | |
| Form 8-K PROTHENA CORP PUBLIC For: Feb 19 | SEC filing · Form 8-K | SEC EDGAR | -2.40% | -3.84% | |
| Prothena Reports Fourth Quarter and Full Year 2025 Financial Results, and Provides Financial Guidance and Business Highlights | Press release | Business Wire | -2.40% | -3.84% | |
| Prothena to Report Fourth Quarter and Full Year 2025 Financial Results on February 19, 2026 | Press release | Business Wire | +2.03% | +1.24% | |
| Form 8-K PROTHENA CORP PUBLIC For: Dec 10 | SEC filing · Form 8-K | SEC EDGAR | -1.25% | -3.86% | |
| Prothena Announces Board of Directors Update | Press release | Business Wire | -1.25% | -3.86% | |
| Form 8-K PROTHENA CORP PUBLIC For: Nov 19 | SEC filing · Form 8-K | SEC EDGAR | +2.57% | -0.69% | |
| Prothena Announces Poster Presentation on its TDP-43 CYTOPE® Program at Neuroscience 2025 | Press release | Business Wire | +2.57% | -0.69% | |
| Prothena Highlights Phase 2 Data for Coramitug (Formerly PRX004) Published in Circulation, Official Journal of AHA | Press release | Business Wire | -1.44% | +0.87% | |
| Form 10-Q PROTHENA CORP PUBLIC For: Sep 30 | SEC filing · Form 10-Q | SEC EDGAR | +0.57% | +0.67% | |
| Form 8-K PROTHENA CORP PUBLIC For: Nov 06 | SEC filing · Form 8-K | SEC EDGAR | +0.57% | +0.67% | |
| Form DEFA14A PROTHENA CORP PUBLIC | SEC filing · Form DEFA14A | SEC EDGAR | +0.57% | +0.67% | |
| Prothena Reports Third Quarter 2025 Financial Results and Business Highlights | Press release | Business Wire | +0.57% | +0.67% | |
| Prothena to Report Third Quarter 2025 Financial Results on November 6 | Press release | Business Wire | +0.66% | +1.99% | |
| Form DEF 14A PROTHENA CORP PUBLIC For: Nov 19 | SEC filing · Form DEF | SEC EDGAR | -0.10% | +0.78% | |
| Form DEFA14A PROTHENA CORP PUBLIC | SEC filing · Form DEFA14A | SEC EDGAR | -0.10% | +0.78% | |
| Prothena’s Partner Bristol Myers Squibb Obtains Fast Track Designation from the U.S. FDA for BMS-986446 (PRX005), an Anti-MTBR-Tau-Targeting Antibody, for the Treatment of Alzheimer’s Disease | Press release | Business Wire | +0.25% | +0.40% | |
| Form PRE 14A PROTHENA CORP PUBLIC For: Nov 19 | SEC filing · Form PRE | SEC EDGAR | +0.27% | +1.62% | |
| Prothena to Participate in the Cantor Fitzgerald Global Healthcare Conference | Press release | Business Wire | +0.48% | -0.85% | |
| Form 8-K PROTHENA CORP PUBLIC For: Aug 27 | SEC filing · Form 8-K | SEC EDGAR | +0.61% | +0.24% | |
| Prothena Provides Update on PRX012 and Announces Results from the Phase 1 ASCENT Clinical Program | Press release | Business Wire | +0.61% | +0.24% | |
| Form S-8 PROTHENA CORP PUBLIC | SEC filing · Form S-8 | SEC EDGAR | -0.65% | -0.39% | |
| Form 8-K PROTHENA CORP PUBLIC For: Aug 06 | SEC filing · Form 8-K | SEC EDGAR | -2.79% | +5.32% | |
| Prothena Announces that Novo Nordisk Will Advance Coramitug (Formerly PRX004) into Phase 3 Development for ATTR Amyloidosis with Cardiomyopathy | Press release | Business Wire | -2.79% | +5.32% | |
| Form 10-Q PROTHENA CORP PUBLIC For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | +0.43% | +0.00% | |
| Form 8-K PROTHENA CORP PUBLIC For: Aug 04 | SEC filing · Form 8-K | SEC EDGAR | +0.43% | +0.00% | |
| Prothena Reports Second Quarter 2025 Financial Results and Business Highlights | Press release | Business Wire | +0.43% | +0.00% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the PRTA section they belong to.
Where else PRTA is measured.
PRTA earnings → · Analyst actions → · SEC filings →
Other Healthcare names, measured the same way
| Ticker | Events | Median 30-min | % positive |
|---|---|---|---|
| Addus HomeCare Corporation (ADUS) | 256 | -0.02% | 47% |
| Celldex Therapeutics, Inc. (CLDX) | 256 | +0.04% | 57% |
| Xeris Biopharma Holdings, Inc. (XERS) | 256 | +0.32% | 57% |
| Cerus Corporation (CERS) | 255 | +0.09% | 52% |
Same sector, same measurement: percent move vs. the price at the news timestamp, read at 30 minutes. Sample sizes differ, so the medians are comparable but the confidence behind them is not.
All Healthcare names, measured the same way →
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How the numbers are made.
How is Prothena Corporation plc - Ordinary Shares's median reaction calculated?
Every labeled PRTA news event is measured from its own timestamp: the last trade before the news is the base price, and the move is read at fixed horizons — 30 minutes of trading, then the close. The median across 256 events is what this page reports. Point-in-time, zero look-ahead: no event borrows information from a later one.
What counts as a positive reaction?
Any event whose price move is above zero at the horizon, relative to the last trade before the news timestamp. 49% of PRTA's measured events are up at 30 minutes; the rest close the window flat or negative.
How often is this page updated?
The news table refreshes automatically as new events are labeled and priced. The reaction medians are re-pulled in batches from the dataset — the figures here are as of 2026-09-21.
Does PRTA's past reaction predict its next one?
No. These are realized facts about past events, not forecasts. They describe a distribution — they say nothing certain about any future move.