Moderna stock is down because investors sold a Phase 3 melanoma result they had already paid for, after the number leaked two days early and turned out to be a clear win rather than a larger one. MRNA stock closed at $202.63 on Thursday 22 October 2026, down $43.18, or 17.57%, from Wednesday’s $245.81, once intismeran autogene data from INTerpath-001 appeared on Oncology Central and Merck and Moderna published the full dataset the same afternoon.
The comfortable reading is that the cancer vaccine failed. It did not. At a median follow-up of 24.6 months, intismeran plus Keytruda cut the risk of recurrence or death by 42% versus Keytruda alone, a hazard ratio of 0.58, with a two-sided p-value below 0.001, in 1,137 patients. The leak did not reveal a statistical miss. It revealed the magnitude the 19 August topline had withheld, inside a share price that had already risen 733.54% from the 31 December 2025 close of $29.49 to Wednesday’s $245.81.
Having tracked this readout since that topline, the size that hit the tape first was the intention-to-treat headline. In the first six months the hazard ratio was 0.99. After six months a pre-specified analysis put it at 0.42, a 58% reduction. The first number moves the price. The rest arrives later, which is the same plumbing as a leaked earnings figure.
Key facts
- Nasdaq official close, Thursday 22 October 2026: $202.63, down $43.18, or 17.57%, from $245.81. Open $240.125, high $241.26, low $180.80, volume 49,947,210. The high never reclaimed Wednesday’s close. Nasdaq, file downloaded 23 October 2026.
- Same file: the open was only 2.31% under Wednesday. The low was 26.45% under it. The only larger down close than 17.57%, back to 1 October 2025, is 20 August 2026, at 23.55%.
- 31 December 2025 close $29.49. Thursday is up 587.11% from that close. Wednesday’s $245.81 was up 733.54%. Reuters, during the session, said the rally had lifted the stock more than 500% in 2026. Reuters.
- Company release, 22 October: recurrence or death reduced 42% (HR 0.58, 95% CI 0.45-0.75). Distant metastasis or death reduced 38% (HR 0.62). Two-year rates 82.2% versus 70.0%, and 88.5% versus 80.2%. After six months, HR 0.42. Overall survival is not mature. Merck.
- ESMO at 2:11 p.m. Eastern: the embargo on late-breaking abstract LBA1 was breached, and the embargo on the full dataset was lifted. @myESMO. The presentation remains Presidential Symposium I in Madrid on Saturday.
- Stock Analysis, beside the close: market cap $80.90 billion, 399.24 million shares. Apply the $43.18 decline to that cap and the close-to-close change is about $17.2 billion. Reuters’ “about $24 billion” was the intraday print at $183.88. Stock Analysis.
What leaked, and what the trial measured
Intismeran autogene, also called V940 and mRNA-4157, is built from a patient’s own tumor. Up to 34 mutations that appear on the cancer and not on healthy cells are written into synthetic mRNA. The shot is given with pembrolizumab, sold as Keytruda, after surgery. The question is whether the cancer comes back, not whether a visible tumor shrinks.
INTerpath-001, NCT05933577, randomized 1,137 patients 2:1 after complete resection of stage IIB-IV cutaneous melanoma. The combination arm received intismeran at 1 mg every three weeks for up to nine doses, plus Keytruda at 400 mg every six weeks for up to nine cycles. The control arm received placebo plus the same Keytruda. Median follow-up at this analysis was 24.6 months. Median recurrence-free survival was not reached in either arm.
Merck and Moderna said on 19 August that the trial had met its primary endpoint and a key secondary endpoint, and they withheld the hazard ratio. This desk recorded the tape that day in the account of the 177% session: the close was $174.38, up from $62.96, on 199,252,300 shares. The full numbers were reserved for the European Society for Medical Oncology in Madrid and for Presidential Symposium I on Saturday 24 October, abstract LBA1.
The hold broke around midday Thursday. MarketWatch reported that Oncology Central, run by Informa, published a story with the embargoed data and did not respond to a request for comment. TIKR put the page at about 12:30 p.m. Eastern, said it was taken down shortly afterward, and reported a volatility halt minutes later. The Motley Fool also reported a brief halt. This desk has not seen an exchange notice, so the halt remains their reporting.
The open shows the leak was not an overnight gap. Thursday opened at $240.125, only 2.31% under $245.81. The high, $241.26, stayed 1.85% under Wednesday’s close. The low was $180.80. From that low back to the $202.63 close is 12.07%, and the day still finished down 17.57%. At 2:11 p.m. Eastern, ESMO posted that LBA1’s embargo had been breached and that the full dataset was no longer under embargo. The companies then published, and said the paper had been accepted by The New England Journal of Medicine.
Keep the two statistics apart. A hazard ratio of 0.58 is a 42% lower event rate across follow-up. The two-year snapshot is 82.2% versus 70.0%, a gap of 12.2 points, not 42. Distant metastasis-free survival is a hazard ratio of 0.62 and a two-year gap of 8.3 points, 88.5% versus 80.2%. Through the immunization course the hazard ratio was 0.99. After it, the pre-specified figure was 0.42, a 58% reduction. A modified analysis that drops patients who never received a planned dose was 0.51. That cut is not the older Phase 2 result.
“This is highly statistically significant. It is not by chance,” Dr. Hussein Tawbi, a melanoma specialist and trial investigator at MD Anderson, told Reuters.
What the companies and ESMO did once the number was out
The companies published rather than waiting for Saturday. The release carries the efficacy table, the six-month split, the safety table, and one operational sentence: they are engaging with regulatory authorities. Intismeran is still investigational. That sentence is not an approval, and the release names no filing date.
Dr. Dean Y. Li, president of Merck Research Laboratories, said INTerpath-001 is “the first Phase 3 study to demonstrate a clinically meaningful improvement in RFS and DMFS over standard-of-care KEYTRUDA in patients with resected melanoma,” and called it “one of the most significant advances in melanoma treatment since the advent of immunotherapy.” Stéphane Bancel, Moderna’s chief executive, said the results “mark a defining moment” for the idea that mRNA could be matched to each patient’s tumor, and that they “reinforce our conviction that mRNA has the potential to fundamentally change how we treat cancer.”
Professor Georgina Long, principal investigator and medical director of Melanoma Institute Australia, kept the claim inside the trial population. The findings, she said, support “a fundamentally new and individualized approach to treating resected melanoma in the adjuvant setting,” and will inform work in other tumors. A melanoma hazard ratio is not, on her wording, a lung-cancer result.
The rest of the programme is the valuation past melanoma, and it did not read out on Thursday. Merck and Moderna said INTerpath is nine Phase 2 and Phase 3 trials, including three ongoing Phase 3 studies in non-small cell lung cancer, plus the earlier Phase 2b KEYNOTE-942 melanoma study and early work in pancreatic, gastric, and perioperative lung cancer. Those trials are where a platform either earns the multiple or does not.
Safety is familiar rather than new, which is not the same as mild. Treatment-related adverse events hit 95.8% of 755 combination patients and 90.0% of 380 patients on Keytruda alone. Grade 3 to 5 treatment-related events were 14.2% and 13.4%. The companies said no new safety signals were seen. The common combination events were fever in 52.2%, injection-site pain in 51.0%, and fatigue in 38.5%. Fever in about half the patients is the practical cost of nine doses.
ESMO opened an investigation. Pharmaphorum reported that the society said it “may have identified the source,” and that “appropriate measures are being taken, and, should the findings warrant it, we will consider all available options.” No name was in the posts and reports used here. Merck’s stock, Reuters said, closed down about 1.8%. Keytruda is already Merck’s franchise. For Moderna the same table is the evidence of a second act after Covid vaccines, which is why the percentage moves were not the same.
A 587% year, and two figures for the value that came off
The Nasdaq file has 31 December 2025 at $29.49. Wednesday’s $245.81 was 733.54% above that close, and the $254.48 high is the high of the file. Thursday’s $202.63 is still 587.11% above 31 December, and 20.37% under that high. A down day of $43.18 took off the top of the year. It did not return the stock to the $62.96 close of 18 August.
Between the topline and the leak, the shares went from the 19 August close of $174.38 to $245.81 with no hazard ratio in public. The bar that wait had set is in the note filed while ESMO was still ahead, and in the August note filed while the ratio was unpublished. Jefferies, as recorded then, wanted a recurrence-free hazard ratio below 0.80, and below 0.70 to reinforce confidence. Thursday’s 0.58 is under both. BioSpace reported hopes for a ratio below 0.60. BioPharma Dive reported a range of a 40% to 50% relative reduction, and said Moderna had called 35% clinically significant. Forty-two percent sits in that band. Clearing a published bar is not the same as satisfying a price that has run past the bar.
The older study is the wrong denominator if it is used as a forecast. Benzinga reported a 49% reduction at five years in the Phase 2b. AJMC, citing RBC, put that hazard ratio at 0.51. The Boston Globe reported an earlier 59% cut in distant-metastasis risk, against 38% here. KEYNOTE-942 was smaller, stage III/IV only, and a different follow-up. The modified Phase 3 ratio of 0.51 resembles it. That cut is not the primary endpoint.
Volume says the tape was the event. Thursday’s 49,947,210 shares were 2.57 times the prior 65 sessions’ average of 19.46 million in the same file. The 19 August session was 199.3 million. Thursday was a crowded exit, not that stampede.
The two “billions wiped” figures are two clocks. Reuters said about $24 billion while Moderna was down 25.2% at $183.88, and called that print set for the steepest one-day percentage fall on record. The official close was 17.57%, which is not the record in the file. Stock Analysis put the closing market cap at $80.90 billion. On that base, $43.18 is about $17.2 billion. Quote the wire with its timestamp or the close with its timestamp. Mixing them invents a third day.
The chart is the Nasdaq file. No scenario is drawn. The 20-session average of closes through Thursday is $210.43, so $202.63 sits 3.70% under it. The 50-session average is $168.42, so the close is still 20.31% above that longer average. October, in the lower panel, shows Wednesday as the highest close and Thursday as the break.
Nasdaq official daily closes for MRNA through Thursday 22 October 2026. The top panel includes daily lows. The lower panel is October. FinanceFeeds chart, 23 October 2026.
| Reading | Figure | What it is |
|---|---|---|
| Official close | $202.63 on 22 October | Down 17.57% from $245.81. The bar that counts. |
| Session low | $180.80 | 26.45% under Wednesday. Not the close. |
| Reuters print | $183.88, down 25.2% | Tied to about $24 billion. Not the close. |
| Close-to-close value | About $17.2 billion | $43.18 on the $80.90 billion close cap. |
| Primary result | HR 0.58, p below 0.001 | 42% relative reduction. Company release. |
| After six months | HR 0.42 | 58% relative reduction. Not the leak’s headline. |
| From 31 Dec 2025 | Up 587.11% | $29.49 to $202.63 in the Nasdaq file. |
UBS analyst Michael Yee called the results “solid data” and the pullback a “sell the news” event, and told Reuters that expectations were high because of the companies’ own commentary. William Blair’s Myles Minter called the data “great” and asked whether other cancers will match it, and whether efficacy differed by mutational burden. The release said the benefit was generally consistent across subgroups. It did not print that split.
Why a clear statistical win can still reprice the shares
The argument is not whether 0.58 happened. The p-value, and Tawbi’s comment, close the chance explanation for this dataset. The argument is what a regulator and a payer do with an individualized product on top of a drug that is already the standard.
Keytruda is the control. The combination had to beat a therapy Merck already sells in resected melanoma. Li called the result a new benchmark. The same release shows the curves did not separate for six months. A label has to say when the benefit appears. The companies’ own analysis says it appears after the immunization course: up to nine patient-specific doses, with fever in 52.2% of the combination arm.
Manufacturing is the question the hazard ratio does not answer. Each sequence is different, capped at 34 neoantigens, and the piecewise benefit showed up after the course, not during it. The release says the companies are talking to regulators. It does not say a file has been accepted.
The release cites more than 338,000 new melanoma cases worldwide in 2024, and about 112,000 US cases and more than 8,500 US deaths estimated for 2026. The trial is the resected high-risk slice of that, and overall survival is only a favorable trend. Moderna does not sell Keytruda, so the hazard ratio does not say what share of a future price belongs to the vaccine. AJMC reported that RBC called the data clinically meaningful and questioned the value against neoadjuvant immunotherapy. This trial does not test that sequencing. Three Phase 3 lung studies are where the platform question gets its own number.
The embargo is the market-structure fact. A page around 12:30 p.m. Eastern priced a partial record. ESMO lifted it at 2:11 p.m. The close at $202.63 is the market after the full table, including the 0.99 and the 0.42. The low is the market during the leak. Only the close is the official bar.
What happens next
Saturday’s symposium is the first investigator walk-through of the subgroups, including mutational burden. The filing, when it exists, still has to carry nine patient-specific doses, the fever rate, and immature overall survival. Three Phase 3 lung trials decide whether this is a platform or one melanoma result. Stock Analysis lists the next earnings date as 6 November 2026. That call can update cash. It cannot finish those trials.
ESMO’s leak inquiry is the process item. A named source would show a Presidential Symposium embargo can be traded at noon. One premarket figure is already up, and it is not a close. Stock Analysis showed $193.08 at 9:21 a.m. Eastern on Friday 23 October, down $9.55, or 4.71%. Every official price in this piece stops at Thursday’s Nasdaq close. Moderna stock news that quotes only the midday low is quoting a different bar.
This is an account of the tape and the trial release. It is not a forecast from this desk, and it is not advice.
Frequently asked questions
Why is Moderna stock down?
Moderna stock is down because Phase 3 melanoma data leaked on 22 October 2026, two days before the ESMO talk, after a rally of more than 500% in 2026. The Nasdaq close was $202.63, down $43.18, or 17.57%, from $245.81. The trial did not miss its test. Intismeran plus Keytruda cut recurrence or death by 42%, hazard ratio 0.58. The price had already assumed a large win. Reuters called the session, at an intraday $183.88, a sell-the-news move.
What did the Moderna cancer vaccine data show?
In 1,137 patients with resected stage IIB-IV melanoma, followed a median 24.6 months, the combination reduced recurrence or death by 42% versus Keytruda, and distant metastasis or death by 38%. Two-year recurrence-free survival was 82.2% versus 70.0%. The curves did not separate in the first six months, hazard ratio 0.99. After the course, a pre-specified analysis showed 58%, hazard ratio 0.42. Overall survival is not mature. The companies said they are talking to regulators.
Did the cancer vaccine trial fail?
No. The primary analysis cleared a high bar, p-value below 0.001, on recurrence-free survival and distant metastasis-free survival. Dr. Hussein Tawbi told Reuters it was highly significant and not chance. What did not match the share price was the size of the win, after a rise from $29.49 on 31 December 2025 to $245.81 on 21 October. A 42% relative reduction can be real and still smaller than the move in the equity.
How much value came off Moderna in the session?
It depends on the print. Reuters said about $24 billion while the shares were down 25.2% at $183.88. At the close of $202.63, Stock Analysis put the market cap at $80.90 billion, and the $43.18 decline is about $17.2 billion on that base. The intraday low was $180.80, 26.45% under Wednesday. The close belongs in a performance table. The $24 billion belongs to the midday wire.
What is the 2026 gain in MRNA stock after the drop?
Nasdaq closes put 31 December 2025 at $29.49 and 22 October 2026 at $202.63, a gain of 587.11%. Wednesday’s $245.81 had been 733.54% above the same start. Thursday removed the top of that rally. It did not return the shares to $62.96, the close on 18 August, the day before the topline. Round phrases such as “over 500%” describe the same path. The file, at the Thursday close, is 587.11%.
When is the full presentation, and is the vaccine approved?
Presidential Symposium I is on Saturday 24 October 2026 in Madrid, late-breaking abstract LBA1. ESMO lifted the embargo on Thursday after the breach. Intismeran autogene is not approved. Merck and Moderna said they are engaging with regulators, and The New England Journal of Medicine has accepted the paper. Acceptance is not a decision date. Phase 2b figures come from a different study and should not be swapped in for these Phase 3 numbers.
