It's the day after one of the surprise healthcare stories of 2026.

Moderna (MRNA) shares fell 20% in early trading on Thursday after a stunning 177% gain yesterday on news that the biotech and partner Merck (MRK) notched a big breakthrough in the fight against cancer.

The pair announced that their personalized mRNA cancer vaccine — called intismeran — successfully hit its primary goal in a Phase 3 late-stage trial, demonstrating a meaningful reduction in melanoma recurrence in patients who had already had their tumors surgically removed.

The trial compared using intismeran alongside Merck's well-known immunotherapy drug Keytruda against using Keytruda alone. Patients who received the combination lived meaningfully longer without their cancer returning or spreading.

More from Yahoo Scout What did Moderna's Phase 3 cancer vaccine trial achieve? What could this mean for Moderna's business diversification? How are Wall Street analysts viewing Moderna's breakthrough? Why did Moderna shares fall after yesterday's gains?

"It's a home run, maybe even a grand slam," Dr. Ezekiel Emanuel said on Yahoo Finance (video above). "The results are pretty amazing."

Here are several viewpoints from Wall Street analysts that cover Moderna that have stood out to us since the news hit.

Jefferies analyst Tycho Peterson: "The update represents an important proof point for mRNA modality beyond legacy COVID. Potential winners likely include the bioprocessing ecosystem (RGEN, DHR, MRK GR, AVTR) and select life science tools suppliers (Aldevron/DHR)."

Bank of America analyst Alec Stranahan: "The share run on intismeran readout in adjuvant melanoma reflects a watershed moment for Moderna, in our view, effectively allowing the company to diversify away from infectious disease and potentially easing persistent capital overhangs. The question now is how big the oncology franchise could get and what areas of upside remain for shares? We caught up with the company following the data and detail our thoughts on both these points below. Overall, we see the setup as fundamentally improved versus 12 months ago, with room to run in both infectious disease and oncology, although the debates around label expansions and market uptake remain."

Citigroup analyst Geoff Meacham: "Meeting DMFS with no new safety signals is encouraging, but validation of Moderna's oncology platform will depend on the full dataset (possibly ESMO in Madrid, 10/23-10/27) and evidence that efficacy translates across tumor types. For now, the readout reduces phase 3 risk without resolving questions around differentiation, commercial uptake, and platform-level read through."

JPMorgan analyst Jessica Fye: "Coming back to MRNA stock, we see the launch of intismeran in adjuvant melanoma as key to MRNA returning to profitability; however, as a partnered asset in a relatively small indication by IO standards that was already in our model at an 85% POS, we see success in adj melanoma as priced in with the stock sitting at ~$25bn market cap prior to the news. Un-risk-adjusting adj melanoma could add ~3% to our valuation, but we are not surprised to see the stock rallying given the positioning. We see the read-across to other indications as critical, and even more important, to thinking about value from here. Our current valuation includes ~$15/share of risk-adjusted credit for other indications, and we will look to details in the presentation for more insight and see subsequent trials outside of melanoma as key to informing how to think about the ultimate value to Moderna from this partnership."