Mersana Therapeutics, Inc. (MRSN)
MRSN moved a median of -0.20% 30 minutes after news, and +0.03% by the close. How MRSN actually reacts to news — the realized, point-in-time move the market made, measured across 251 labeled events over the last three years with zero look-ahead.
MRSN’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | -0.28% | 44% | 215 |
| 30-min | -0.20% | 46% | 220 |
| 60-min | -0.51% | 41% | 220 |
| to close | +0.03% | 51% | 213 |
| Middle 50% of MRSN reactions | -3.22% to +2.11% |
|---|---|
| Median reaction (30-min) | -0.20% |
| Measured reactions | 251 |
Half of all Mersana Therapeutics, Inc. news events land between -3.22% and +2.11% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
How MRSN reacts, by analyst action.
| Event | Events | Median 30-min | % positive | Median to close |
|---|---|---|---|---|
| Analyst upgrades | 16 | +0.18% | 56% | -2.17% |
| Analyst downgrades | 14 | +0.36% | 71% | +2.61% |
| Rating reiterations | 20 | +0.04% | 50% | -1.07% |
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. 3 further classes were observed with fewer than 10 measured events and are not published. See how MRSN ranks against every other measured name →
That’s how MRSN usually reacts — get an email when it moves on news →Email me when MRSN moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to MRSN's baseline. Nothing else.
Recent MRSN events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Form 15-12G Mersana Therapeutics, | SEC filing · Form 15-12G | SEC EDGAR | — | — | |
| Form EFFECT Mersana Therapeutics, | SEC filing · Form EFFECT | SEC EDGAR | — | — | |
| Form 8-K Mersana Therapeutics, For: Jan 05 | SEC filing · Form 8-K | SEC EDGAR | — | — | |
| Form POS AM Mersana Therapeutics, | SEC filing · Form POS | SEC EDGAR | — | — | |
| Form S-8 POS Mersana Therapeutics, | SEC filing · Form S-8 | SEC EDGAR | — | — | |
| Halper Sadeh LLC Encourages UDMY, ALEX, UBFO, MRSN Shareholders to Contact the Firm to Discuss Their Rights | Press release | PR Newswire | — | +0.52% | |
| BRODSKY & SMITH SHAREHOLDER UPDATE: Notifying Investors of the Following Investigations: Mersana Therapeutics, Inc. (Nasdaq - MRSN), Cidara Therapeutics, Inc. (Nasdaq - CDTX), Cadence Bank (NYSE – CADE) | Press release | GlobeNewswire | -0.18% | -0.14% | |
| Halper Sadeh LLC Encourages MRSN, CDTX, RYI Shareholders to Contact the Firm to Discuss Their Rights | Press release | GlobeNewswire | — | -0.16% | |
| Form 10-Q Mersana Therapeutics, For: Sep 30 | SEC filing · Form 10-Q | SEC EDGAR | +0.40% | +2.61% | |
| Form 8-K Mersana Therapeutics, For: Nov 14 | SEC filing · Form 8-K | SEC EDGAR | +0.40% | +2.61% | |
| Halper Sadeh LLC Encourages MRSN, THS, HBAN Shareholders to Contact the Firm to Discuss Their Rights | Press release | GlobeNewswire | +0.40% | +2.61% | |
| Mersana Therapeutics Provides Business Update and Announces Third Quarter 2025 Financial Results | Press release | GlobeNewswire | +0.40% | +2.61% | |
| Day One Biopharmaceuticals to Acquire Mersana Therapeutics | Press release | GlobeNewswire | -2.00% | — | |
| Form 8-K Mersana Therapeutics, For: Nov 12 | SEC filing · Form 8-K | SEC EDGAR | -2.00% | — | |
| MRSN Stock Alert: Halper Sadeh LLC is Investigating Whether the Sale of Mersana Therapeutics, Inc. is Fair to Shareholders | Press release | Business Wire | -2.00% | — | |
| Mersana Therapeutics to Host Third Quarter 2025 Conference Call on November 14, 2025 | Press release | GlobeNewswire | +0.59% | +1.29% | |
| Form 8-K Mersana Therapeutics, For: Sep 05 | SEC filing · Form 8-K | SEC EDGAR | -0.59% | +3.38% | |
| Form 10-Q Mersana Therapeutics, For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | -6.43% | +21.61% | |
| Form 8-K Mersana Therapeutics, For: Aug 13 | SEC filing · Form 8-K | SEC EDGAR | -6.43% | +21.61% | |
| Mersana Therapeutics Provides Business Update and Announces Second Quarter 2025 Financial Results | Press release | GlobeNewswire | -6.43% | +21.61% | |
| Mersana Therapeutics to Host Second Quarter 2025 Conference Call on August 13, 2025 | Press release | GlobeNewswire | +0.14% | -3.32% | |
| Form 8-K Mersana Therapeutics, For: Jul 24 | SEC filing · Form 8-K | SEC EDGAR | +5.07% | +0.03% | |
| Mersana Therapeutics Announces 1-for-25 Reverse Stock Split | Press release | GlobeNewswire | +5.07% | +0.03% | |
| Form 8-K Mersana Therapeutics, For: Jul 01 | SEC filing · Form 8-K | SEC EDGAR | +2.25% | +0.56% | |
| Form 8-K Mersana Therapeutics, For: Jun 12 | SEC filing · Form 8-K | SEC EDGAR | +1.48% | +8.08% | |
| Form 8-K Mersana Therapeutics, For: Jun 02 | SEC filing · Form 8-K | SEC EDGAR | +3.09% | +8.85% | |
| Mersana Therapeutics Reports Additional Positive Interim Phase 1 Clinical Data for Emi-Le in Oral Presentation at 2025 ASCO Annual Meeting | Press release | GlobeNewswire | +3.09% | +8.85% | |
| Mersana Therapeutics to Present at Upcoming Investor Conferences | Press release | GlobeNewswire | -3.50% | +1.72% | |
| CORRECTION - Mersana Therapeutics Provides Business Update and Announces First Quarter 2025 Financial Results | Press release | GlobeNewswire | -6.00% | -13.98% | |
| Form 10-Q Mersana Therapeutics, For: Mar 31 | SEC filing · Form 10-Q | SEC EDGAR | -6.00% | -13.98% | |
| Form 8-K Mersana Therapeutics, For: May 15 | SEC filing · Form 8-K | SEC EDGAR | -6.00% | -13.98% | |
| Mersana Therapeutics Provides Business Update and Announces First Quarter 2025 Financial Results | Press release | GlobeNewswire | -6.00% | -13.98% | |
| Form 8-K Mersana Therapeutics, For: May 05 | SEC filing · Form 8-K | SEC EDGAR | -6.48% | -10.76% | |
| Mersana Therapeutics Announces Strategic Restructuring and Reprioritization Plan Focused on Advancing Emi-Le in Triple-Negative Breast Cancer | Press release | GlobeNewswire | -6.48% | -10.76% | |
| Form ARS Mersana Therapeutics, For: Dec 31 | SEC filing · Form ARS | SEC EDGAR | +3.24% | +2.61% | |
| Form DEF 14A Mersana Therapeutics, For: Jun 12 | SEC filing · Form DEF | SEC EDGAR | +3.24% | +2.61% | |
| Form DEFA14A Mersana Therapeutics, | SEC filing · Form DEFA14A | SEC EDGAR | +3.24% | +2.61% | |
| Mersana Therapeutics Announces Upcoming Emi-Le Oral and Poster Presentations at ASCO 2025 Annual Meeting | Press release | GlobeNewswire | +1.40% | -2.77% | |
| Form PRE 14A Mersana Therapeutics, For: Jun 12 | SEC filing · Form PRE | SEC EDGAR | +0.99% | -4.69% | |
| Mersana Therapeutics Announces Inducement Grant Under Nasdaq Listing Rule 5635(c)(4) | Press release | GlobeNewswire | -3.62% | +4.34% | |
| Mersana Therapeutics Announces Upcoming Oral Presentation of Emi-Le Clinical Data at European Society for Medical Oncology (ESMO) Breast Cancer 2025 Annual Congress | Press release | GlobeNewswire | -1.36% | -3.07% | |
| Form 10-K Mersana Therapeutics, For: Dec 31 | SEC filing · Form 10-K | SEC EDGAR | -6.46% | -10.11% | |
| Form 8-K Mersana Therapeutics, For: Mar 03 | SEC filing · Form 8-K | SEC EDGAR | -6.46% | -10.11% | |
| Mersana Therapeutics Provides Business Update and Announces Fourth Quarter and Full Year 2024 Financial Results | Press release | GlobeNewswire | -6.46% | -10.11% | |
| Form 8-K Mersana Therapeutics, For: Feb 25 | SEC filing · Form 8-K | SEC EDGAR | -6.46% | -10.11% | |
| Mersana Therapeutics to Present at Upcoming Investor Conferences | Press release | GlobeNewswire | -2.88% | -6.20% | |
| Mersana Therapeutics to Host Fourth Quarter and Year End 2024 Conference Call on March 3, 2025 | Press release | GlobeNewswire | -2.88% | -6.20% | |
| Mersana Therapeutics Announces Inducement Grant Under Nasdaq Listing Rule 5635(c)(4) | Press release | GlobeNewswire | -1.78% | -7.89% | |
| Form 8-K Mersana Therapeutics, For: Feb 05 | SEC filing · Form 8-K | SEC EDGAR | +1.78% | +17.80% | |
| Mersana Therapeutics to Participate in the Guggenheim SMID Cap Biotech Conference | Press release | GlobeNewswire | -2.63% | +5.97% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the MRSN section they belong to.
Where else MRSN is measured.
MRSN earnings → · Analyst actions → · SEC filings →
Other Healthcare names, measured the same way
| Ticker | Events | Median 30-min | % positive |
|---|---|---|---|
| DOVA PHARMACEUTICALS (DOVA) | 251 | -0.10% | 46% |
| Krystal Biotech, Inc. (KRYS) | 251 | +0.05% | 52% |
| Soligenix, Inc. (SNGX) | 251 | -0.71% | 35% |
| Co-Diagnostics, Inc. (CODX) | 250 | 0.00% | 46% |
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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Every name we’ve measured, in one place.
How the numbers are made.
How is Mersana Therapeutics, Inc.'s median reaction calculated?
Every labeled MRSN 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 251 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. 46% of MRSN'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 MRSN'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.