Explore real markets.
Learn what the numbers mean.
Start with
Or turn the dial to pick a reading.
OFF and SUBJECT are fixed. SAVE keeps the layout in this browser.
What the number on the screen means, in plain words. DEEPER shows how it is worked out.
Investigates loaded measurements. No current news or connected AI service.
Things you are following. ADD puts one on the list, OPEN looks at it.
Bitcoin
—The range follows the tabs on the screen.
Daily closes from the data job, not live prices. Up to 8 stocks. The list stays in this browser.
Any coin CoinGecko tracks. The choice is stored in this browser, joins the live poll and the range tabs, and can stand in for BTC in the statistics.
Rolling 30-session correlation.
30-session realized volatility, annualized. BTC left, ^IXIC right.
BTC / USD below running peak.
^IXIC below running peak.
PROBE investigates the measurement on the screen. It answers from the figures this instrument holds, and says so plainly when those figures cannot answer the question.
PROBE holds no news, filings or announcements. Price data shows what happened; on its own it never shows why. Where a question needs evidence this instrument does not have, PROBE says that rather than guessing.
Today’s reading
Once per session, after the US close, the data job hands Claude the figures above and asks for three plain sentences that describe them: no predictions, no advice, nothing added. A checker rejects any reply that breaks those rules, and a fixed template built from the same numbers is published instead. The prompt and the checker are in src/lib/note.js; the longer view is in the findings.
Alerts live in this browser only and fire while the page is open: three beeps, a flash, and a notification if you allowed them.
What this is
A live market meter. Turn the dial to pick a reading: drag it, roll the mouse wheel over it, or use the arrow keys. The tabs on the screen set the chart's range for the coins, switch MOVER and LOSER between stocks and crypto, and step through WATCH. DATA opens the charts behind the reading. Crypto refreshes every 45 seconds. Index figures refresh about every 15 minutes during US market hours, and the statistics are recomputed from daily closes after each session.
Dial
BTC, ETH: spot bitcoin and ether in US dollars, volume-weighted across the exchanges CoinGecko tracks. Both trade every calendar day.
NASDAQ: the Nasdaq Composite (^IXIC), about 3,000 listed securities. S&P: the S&P 500 (^GSPC). Both are index levels, not tradable prices.
MOVER and LOSER: the highest and the lowest move of the past week. For stocks, the data job keeps the daily closes of every Nasdaq-100 member it can price and ranks their five-session moves once it has them all, usually before Monday's open. For crypto, it ranks 15 large coins other than bitcoin and ether by their seven-day move. The tabs on the screen switch between the two, and the drawer shows the five highest and the five lowest together.
Both ends describe the past week. Neither is a recommendation.
WATCH: up to eight Nasdaq-100 stocks you choose. Open DATA on that stop and search by symbol or name. The arrows on the screen step through the list and the tabs set the range. These are daily closes from the data job, not live prices. The list stays in this browser.
PROBE: a coin you choose. Open DATA on that stop and search any coin CoinGecko tracks. It takes the stop, and its symbol replaces PROBE on the dial. The choice stays in this browser.
LEARN: the idea behind the figure you were just looking at, explained with that figure. Turn to it, or press LEARN at any stop. It names the concept, prints the live measurement, says what size that measurement counts as, gives one line on how to read it, and offers a way back into the instrument. The drawer holds the same concept in full, with why it matters, the common misconception, and how this page measures it. Underneath sits the daily reading: after each US close, Claude writes three plain sentences about the session's figures. The rules forbid predictions and advice. A checker enforces them, and a reply that breaks them is replaced by a fixed template.
CORR: the selected coin against the selected index over the last 90 sessions, with beta and R² in the drawer. VOL: that coin's realized volatility over 30 sessions, annualized. DD: how far it is below its running peak. The pair is bitcoin and the Nasdaq Composite until you change it at the top of those panels. Any coin's daily closes come from its one-year CoinGecko chart.
Keys
The five keys are soft keys: the first two and the last never move, and the middle two follow the stop, so the row always operates what is on the screen. DATA turns the display into the instrument search. LEARN explains the figure on the screen. HOLD freezes the display.
Between them, on a price: MIN/MAX captures the lowest and highest reading while it is on, and ALERT sets a level on the current stop, so that when the reading crosses it the meter beeps three times, flashes, and sends a notification if you allowed them; the bell on the screen lists them. On CORR, VOL and DD: COMPARE switches the index the coin is measured against, and INFO opens this drawer. On MOVER and LOSER: WATCH puts that stock on your list or takes it off. On WATCH: LIST shows the list and REMOVE drops the stock on the screen. With the list on the display the row becomes OPEN, ADD, REMOVE and INFO; in search it becomes CANCEL; in LEARN, BACK.
On the screen itself, REL zeroes the reading where it stands, so the change line shows the move since you pressed it. The speaker mutes the dial's click and the alarm. Clicking the display opens this drawer. Alerts, the probe and these settings live in this browser only.
Learning as you go
The idea is to learn finance by using the instrument, so nothing here is a course. Under each title, one line says what the stop answers. A question mark beside a figure opens what it measures and how this page computes it, so a concept arrives next to the number it describes. LEARN goes further: it takes the measurement on the screen and says what size it counts as, which is the step from reading a number to judging one.
Those words are rules of thumb. LOW, MODERATE, HIGH, DEEP and the rest are thresholds this instrument adopts so a figure has somewhere to stand, and the panel says so wherever one appears. They are conventions, not facts about markets.
On bitcoin and on VOL, a line says how large the last session's move was against the last 251 daily moves, which is how you tell an ordinary day from a rare one. On DD, the chart marks the peak the current fall began from and the lowest point since, so the drawdown is shown happening rather than defined. The line at the foot of the drawer names the source of the figures above it and when they were read.
FEEDBACK opens a note you can send about what confused you. It carries nothing but what you type, and counts of which stops you opened if you choose to paste them. Those counts are kept in this browser, are never sent anywhere on their own, and hold no personal information.
Skins
The palette beside the name opens the skins: gold, blue, pink, green, red, purple and silver. A skin recolours the holster and the accents. The choice stays in this browser.
Method
Correlation and beta use log returns taken after intersecting both instruments on dates each actually traded. Bitcoin trades weekends and the index does not, so without that step BTC's Monday return spans one day while the index's spans three.
Beta is BTC regressed on the index: the slope of the line through the return scatter. R² is the share of BTC's variance the index explains; a high beta with a low R² is a loose relationship, not a tight one.
Volatility is the sample standard deviation of the 30-session window, annualized by √252. Drawdown runs on each instrument's own history, since a drawdown belongs to one asset's own path.
Findings
The same statistics feed a write-up, Is bitcoin a tech stock?, on how often bitcoin and the Nasdaq move together and when that stops. Every number on it comes from the daily history the meter uses.
Sources
CoinGecko's public API for the coins, called directly from your browser, and for the weekly crypto scan. Financial Modeling Prep for the ^IXIC and ^GSPC quotes and daily closes, BTCUSD daily closes, the Nasdaq-100 members' daily closes and the stock movers' quotes; Alpha Vantage for QQQ where a key is configured. Those two need API keys, which cannot ship in a public page, so a scheduled GitHub Action calls them with keys kept as repository secrets and publishes only the results. Company logos load from Financial Modeling Prep's public image service. The market status is computed in your browser from NYSE hours and holidays; it reports the session and does not control anything.
Built by
Jack McMurry, with Claude Code.
Standing
Market data for reference only. Nothing here is investment advice, a recommendation, or a solicitation to trade. Figures are as reported by the sources above and may be delayed, revised, or wrong.