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.
Things you are following. ADD puts one on the list, OPEN looks at it.
Bitcoin
—What you are measuring
- Subject
- Measurement
- Reading
- Period measured
The range follows the tabs on the screen.
Try a hypothetical mix of stocks.
Daily closes from the data job, not live prices. Up to 8 stocks. The list stays in this browser.
Build a practice portfolio
Start with a hypothetical $10,000. Choose 1–5 US stocks and give each a percentage of the starting investment.
A historical simulation, not actual holdings or a forecast. Fractional shares are bought at the first shared close and held without rebalancing. Uses the same closing-price histories as the stock charts. Excludes deposits, fees, taxes, dividends and actual trading.
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.
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.
Learn by doing, in three short steps.
Today’s market recap
Based on the latest published daily closes. Read the full findings and methodology.
Lessons
Lead a 15-minute workshop · A facilitator guide and printable student worksheet.
Start with price versus return, or pick up a lesson you have already started. Your current task stays in the lesson bar.
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
Explore real market history and learn what the measurements mean. Start experiment opens a five-minute price-versus-return activity. Open Explore above the dial for these actions: Choose an asset opens search; Explore charts opens the current reading’s details; Explain this explains the measurement; Lessons opens the activity library.
You can also turn the dial by dragging it, using the mouse wheel, or pressing its arrow keys. Coin quotes are requested about once a minute. Stock and index snapshots can be delayed; use the dates shown with a reading to tell what period it describes. Measurements use historical closing prices.
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 stocks you choose, from the Nasdaq-100, a list of majors, or any other listed company. Use Choose an asset to search by symbol or company 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. Use Choose an asset to search coins by name or symbol. 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 dial’s LEARN position opens the same contextual explanation as Explain this. More detail adds technical context; Full explanation opens the longer guide. The Explore menu offers Choose an asset, Explore charts, Explain this, and Lessons. You do not need to learn the instrument keys to start an activity. After you start or resume, the current lesson stays in a compact strip above the meter; Back to task returns to its instructions.
On the instrument, DATA opens search and LEARN explains the current measurement. INDEX switches the comparison on CORR, VOL and DD; PROBE opens questions about those readings. Other keys change with the screen: read their current labels. Clicking the display also opens the details.
HOLD freezes the display. REL shows changes from the reading you captured. MIN/MAX tracks readings while enabled; alerts notify you of a level crossing while the page is open. These tools are optional. Settings and lesson progress are kept in this browser when storage is available.
Learning as you go
Explain this introduces the concept behind the current measurement. PROBE answers questions about the available figures, such as whether a move is unusually large. Lessons gives you a task to work through. Opening the library does not reset your task or change your selected company.
The three guided lessons offer short activities; you can also explore freely. 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 charts show the decline below each asset’s previous high, with the current and deepest decline stated beneath them. 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 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. Where that plan does not cover a company, and for any company you search that the job does not pre-fetch, the closes come from Yahoo's public chart endpoint instead, which needs no key. 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.