---
title: "QUICK SPARK: Moderna Stock Drops 25%, Eyes Worst Day in Company's History"
type: "News"
locale: "en"
url: "https://longbridge.com/en/news/296526111.md"
description: "Moderna stock dropped approximately 25.69%, potentially marking the worst day in its history, after surging 176.97% the previous day on positive Phase 3 results for an mRNA cancer vaccine. The sharp reversal occurred despite the historic milestone achieved with Merck & Co., partly influenced by high short interest of about 12.5%."
datetime: "2026-08-20T17:48:54.000Z"
locales:
  - [zh-CN](https://longbridge.com/zh-CN/news/296526111.md)
  - [en](https://longbridge.com/en/news/296526111.md)
  - [zh-HK](https://longbridge.com/zh-HK/news/296526111.md)
generator: "portal-rs"
---

# QUICK SPARK: Moderna Stock Drops 25%, Eyes Worst Day in Company's History

**Moderna, Inc.** (NASDAQ:MRNA) had the biggest day in its history Wednesday. The bill arrived Thursday morning.

The stock handed back as much as 25.69%, eyeing the worst session in company’s history.

On Wednesday, Moderna shares closed up 176.97%, a record, after the biotech company and **Merck & Co., Inc.** (NYSE:MRK) reported positive late-stage results for intismeran autogene, a cancer vaccine built from the mutations found in each patient’s own tumor. 

It is the first mRNA cancer therapy to clear a Phase 3 trial, the final testing stage before regulators decide. 

Yet, Moderna was one of the most shorted names in the market, with short interest at about 12.5% of float.

 **Read Also: AC Immune Says Early Data from Anti-Inflammatory Drug Gives Wider Clinical Momentum for Pipeline** 

*Photo: Shutterstock*

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---
> **Disclaimer: This article is for reference only and does not constitute any investment advice.**