About Subsecond

What Subsecond is

Subsecond is a real-time stock scanner that helps active day traders spot volume and price surges across the entire US market seconds before they print on a chart.

It re-evaluates every one of your scans once per second against 5,000+ US-listed tickers, from 4 AM to 8 PM ET, across the pre-market, regular and after-hours sessions. Five rolling windows run at the same time: 10 seconds, 30 seconds, 1 minute, 5 minutes and 15 minutes. Around 50 metrics are filterable, including price, volume, gap percent, relative volume, dollar volume, float and short interest. It runs in a browser, the engine is written in Rust, and real-time market data is included in the one plan rather than sold separately.

Who makes it

Subsecond is made by purpl LLC, a Wyoming limited liability company. It is built by Malek Layth.

purpl LLC was founded in 2026. Subsecond started as a personal tool, built because Malek could not find a scanner that would evaluate a 10-second rolling window across the whole US market, or that treated pre-market and after-hours as sessions with baselines of their own. It grew into a product from there. It still does the same job: the fast numbers, including the extended-hours ones, without having to go looking for them.

Why we publish a blog

We publish two kinds of article. Market mover reports explain why a specific stock is running today, starting from what the scanner itself saw. Guides explain the concepts the scanner is built on, in plain language, for traders who want to understand a number before they trade on it.

How those articles are produced, reviewed and corrected is set out in our editorial policy. How the scanner computes what it reports is set out in our methodology.

Contact

Support, corrections and press: see the contact page.