Using Signal8/Getting started
How Radar Works: Premarket Stock Alerts on Signal8
How Signal8 Radar works: when it scans, what an alert means, every board column explained, why a cell shows a dash, and what is free versus Signal8 Pro.
What Radar is
Radar is a board of premarket stock alerts. On US trading days it watches the market from 5am ET and flags a stock the moment it meets one of Radar's rules for a premarket move. Each alert records the time it fired and the price at that moment, and the board then shows how the stock has moved since.
An alert means one thing: a stock met one of Radar's rules at that moment. It is information, not a recommendation, and it says nothing about where the stock goes next. The figures on the board are observations of price, not results of trades.
The premarket scanner ranks every mover in the current session. Radar instead fires an alert the moment a single stock meets its rules, and keeps a record of each session.
When Radar runs
Radar runs on US trading days. The board's single list, All Runners, starts scanning at 5am ET, an hour after the premarket session opens at 4am ET.
- Weekends and full market holidays: Radar does not run. Before the next scan starts, the board shows a countdown to the next trading day's 5am ET start, read from the same market calendar the rest of Signal8 uses.
- Early-close days: a half day is still a trading day, so Radar scans from 5am ET as usual.
- After an alert fires: the stock's move is tracked through the rest of the day, including after hours, up to 7:59pm ET.
What an alert means
Radar's rules look at how a stock is trading in the premarket, for example how its price and volume compare with its own recent history. The specific conditions are not published, and they are not a forecast of anything. When a stock meets one of them, the stock joins the board with an alert time and an alert price.
A stock appears on the list once per session. If more than one of Radar's rules flags the same stock, the board keeps the earliest alert, because that is the first moment a reader could have seen it. Everything after that is measured from that first alert price.
Rows are ordered by the biggest move since the alert; new alerts with nothing measured yet sort below them, newest first.
Reading the board column by column
The board groups its columns under three bands: SYMBOL, ALERT and SINCE ALERT.
| Column | What it shows |
|---|---|
| Symbol | The ticker and company |
| Mkt Cap | Market capitalization (see below for live versus past sessions) |
| Alerted (ET) | The minute the alert fired, Eastern Time |
| Alert Price | The close of the one-minute bar in which the alert fired |
| Peak | The highest price since the alert, as a percentage above the alert price, with that price and the time it printed |
| Now | The latest price against the alert price (called Last on past sessions) |
Alert Price
The alert is published at the close of the minute in which the stock met a rule, so the alert price is the closing price of that one-minute bar. It is the reference every other figure on the row is measured from.
Peak
Peak is the highest one-minute high printed strictly after the alert minute, through 7:59pm ET. The alert minute itself is excluded on purpose: its high may have printed before the alert existed, and counting it would credit a move nobody alerted could have seen. On the live board the peak can also update from a live trade between minute closes, and once it has risen it does not fall back while the board is open.
Now and Last
On today's board, Now compares the latest trade with the alert price, so it moves with the stock. On a past session the same column is Last: the last measured price that session, frozen.
Mkt Cap
On today's board, Mkt Cap is the stock's current market cap (price times shares outstanding). On a past session it is the market cap at the alert: the alert price times the shares outstanding on record for that session, so an old session never shows today's figure.
Why some cells show a dash
A dash means not measured. It is never a zero and never a claim that the stock did not move.
- Peak or Now on a fresh alert: the run is measured from the first full minute after the alert. Until a trade prints after that minute there is nothing to measure, and the live board says "No trade yet".
- Mkt Cap: shown as a dash when the price or the share count is missing. For a past session it also needs a dated share count for that session; Radar does not borrow a later one.
- No qualifying bars: if no one-minute bar printed after the alert, every run figure stays unmeasured rather than reading 0%.
A real zero is shown as a number. A dash means "we did not see it", not "it did not happen".
Free and Signal8 Pro
| Without Pro | With Signal8 Pro | |
|---|---|---|
| Today's alerts | Not shown | Live, with tickers |
| Previous sessions | Full, tickers included | Full, tickers included |
| Push alerts | Not available | Phone or browser |
| Community chat | Locked | Included |
With Signal8 Pro ($59 a month), every alert appears live with its ticker. Without Pro, today's alerts are not shown: the board behind the Pro panel is sample data, not real alerts. See Signal8 Pro for what else the plan includes.
Previous sessions are free. The Previous tab shows past sessions in full, tickers included, with no subscription. Their figures are frozen for that session: the alert time, alert price, the peak reached that day and the last measured price.
Alerts, sound, chat and the ticker panel
- Push alerts. The bell on the board header lets a Pro account turn on push alerts for the list. Turning it on also registers the device you are on, in the browser or the Signal8 mobile app. A notification states the list, ticker, alert time and price.
- NEW ALERT sound. The NEW ALERT toggle plays a chime when a stock joins the list while the page is open. Browsers block sound until you interact with a page, so click once anywhere on the board after loading it, otherwise the first chime can be silent. The setting is remembered in that browser.
- Community chat. Pro accounts get a live chat beside the board; without Pro the chat panel is locked. Besides members' messages, the chat carries automatic posts when a stock joins the list and each time a listed stock reaches another +10% above its alert price.
- Ticker panel. Clicking a row opens a panel with a chart marked ALERT (the alert price and time) and PEAK (the highest point since), the alert figures, and the Signal8 Summary from the company page. From there you can open the company page or the Terminal.
Streaks
In the community chat, a 🔥 and a number beside a member's name is their streak: how many US trading days in a row they have been active on Radar.
- An active day is a trading day (Eastern Time) on which the member, signed in with Signal8 Pro, opened the live board or sent a chat message.
- Weekends and market holidays are skipped, so they never break a streak.
- Today counts once you show up. Until then the streak runs to the previous trading day, so it does not reset overnight.
- Shown from 2 days. One day on its own is not shown, and signed-out visitors and the Signal8 bot have no streak.
How to use Radar on Signal8
- Open Radar before 5am ET to see the countdown, or any time to browse previous sessions.
- For a wider view of every premarket mover, with relative volume and float, use the premarket scanner; premarket trading and relative volume explains those figures.
- For alerts on specific companies' filings rather than price moves, see how to set up stock alerts.
FAQ
What time does Signal8 Radar start?
At 5am ET on US trading days, one hour after the premarket session opens. It does not run on weekends or full market holidays; early-close days are trading days, so it runs as normal.
Is a Radar alert a recommendation to buy?
No. An alert means a stock met one of Radar's rules at that moment. It is information, not investment advice, and says nothing about where the stock goes next.
Why does the Peak column show a dash?
A fresh alert, or a stock that has not traded since the alert minute, has nothing measured yet. A dash means not measured; it is never a zero.
Can I see Radar alerts for free?
Yes for past sessions: the Previous tab shows them in full, tickers included. Today's alerts need Signal8 Pro; without it they are not shown.
Terms in this guide
- Relative volume (RVOL)
- Relative volume (RVOL) is a stock's trading volume divided by its typical volume for the same period, so a reading of 3.0 means three times the usual activity.
- Public float
- Public float is the shares held by investors other than a company's officers, directors and controlling holders, or their market value; the SEC uses the dollar figure for form eligibility.
- Trading halt
- A trading halt is a temporary stop in trading of a security ordered by its listing exchange or the SEC, for example pending material news, to request information, or after a volatility pause.
Try it on Signal8
See this in live data with Radar premarket alerts.
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Educational content only. Signal8 is not a broker-dealer or investment adviser, and nothing here is a recommendation to buy or sell any security.