# Catalyst

> An event or piece of news that causes, or is expected to cause, a significant move in a stock's price.

Source: https://www.quantisnow.com/glossary/catalyst
Topic: Glossary / Market structure
Also known as: stock catalyst, news catalyst, catalysts, upcoming catalyst
Last updated: 2026-10-27

A catalyst is an event or piece of news that causes, or is expected to cause, a significant change in a stock's price by changing what investors believe the company is worth. Catalysts can be scheduled, like an earnings date, or unscheduled, like a surprise acquisition.

## How it works

Common stock catalysts:

| Type | Examples |
|---|---|
| Scheduled | Earnings reports, [PDUFA dates](https://www.quantisnow.com/glossary/pdufa-date), trial data readouts, investor days, index rebalances, lock-up expirations |
| Corporate actions | [Merger agreements](https://www.quantisnow.com/glossary/merger-agreement), buybacks, spin-offs, stock offerings, reverse splits |
| External | Analyst rating changes, activist 13D filings, insider buying, regulatory decisions, lawsuits, macro data |

Most catalysts reach the market as a [press release](https://www.quantisnow.com/glossary/press-release) or an SEC filing, and the first reaction often happens in pre-market or after-hours trading.

## Why it matters for traders

Catalyst traders try to anticipate or react to these events. A few patterns are worth knowing:

- **Expectations matter more than the news.** A stock can fall on a beat if the market expected more, or rise on a miss if guidance improves.
- **"Buy the rumor, sell the news."** Stocks that run into a scheduled event often fall after it, even on good outcomes.
- **Binary events cut both ways.** A small biotech awaiting an FDA decision can double or lose most of its value in one day, and options prices reflect that risk through elevated implied volatility.
- **Volume confirms.** A real catalyst usually comes with high [relative volume](https://www.quantisnow.com/glossary/relative-volume). A big move without news or volume is suspect.

## Example

Hypothetical Northwind Therapeutics (ticker NWTX) trades at $18 ahead of a PDUFA date. The stock had risen from $11 over three months as investors positioned for approval. The FDA approves the drug, and the stock opens at $19, then slides to $16.50 by the close: the approval was already priced in.

## FAQ

### What is the difference between a hard and soft catalyst?

A hard catalyst is a concrete, dated event with a clear outcome, such as an FDA decision or earnings. A soft catalyst is less defined, such as a product launch or sector sentiment.

## Related terms

- [Press release](https://www.quantisnow.com/glossary/press-release.md): An official company announcement distributed through a newswire, used to disclose earnings, deals, trial results and other news to the public.
- [PDUFA date](https://www.quantisnow.com/glossary/pdufa-date.md): The target date by which the FDA aims to approve or reject a new drug or biologic application under the Prescription Drug User Fee Act.
- [Earnings surprise (beat or miss)](https://www.quantisnow.com/glossary/earnings-surprise.md): The difference between a company's reported earnings and the analyst consensus estimate, described as a beat when above and a miss when below.
- [Analyst upgrade](https://www.quantisnow.com/glossary/analyst-upgrade.md): A sell-side analyst's move to a more favorable rating on a stock, such as from Hold to Buy, usually published with a new price target and thesis.
- [Merger agreement](https://www.quantisnow.com/glossary/merger-agreement.md): The binding contract between an acquirer and a target that sets the deal price, structure, closing conditions and termination rights of an acquisition.
- [Relative volume](https://www.quantisnow.com/glossary/relative-volume.md): A ratio comparing a stock's current trading volume to its typical volume for the same period, used to spot unusual activity.

## On Quantisnow

- [Trading news catalysts](https://www.quantisnow.com/guides/trading-news-catalysts)
- [Build a news watchlist](https://www.quantisnow.com/guides/building-a-news-watchlist)
- [Earnings calendar](https://www.quantisnow.com/earnings)
- [Live feed: FDA Approvals](https://www.quantisnow.com/news/fda)