What Is Relative Volume (RVOL)? How to Read Unusual Volume
Relative volume (RVOL) compares a stock's volume to its own 20-day average. See the intraday U-shape, the time-of-day fix, and measured RVOL percentiles.
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Evergreen explainers of how US markets actually work — each concept taught with real, queryable market data.
The Most Common SEC Filings, Explained by Data
The most common SEC filing isn't the 10-K or 10-Q — it's the insider Form 4. A data-backed guide to EDGAR's busiest form types, ranked and explained.
What Is the Closing Auction? The Day's Biggest Trade
What the closing auction is, why one 4 p.m. print sets the official close, and how market-on-close orders feed the day's biggest trade — on real tape data.
After-Hours and Premarket Trading: What the Data Shows
After-hours trading runs 4-8 p.m. ET, premarket 4-9:30 a.m. See what the tape shows: session volume shares, spread costs, and when headlines actually land.
What Is VWAP? Volume-Weighted Average Price Explained
Learn what VWAP means, how volume-weighted average price is calculated, and how it differs from a moving average - measured bar by bar from real trades.
When Is the Stock Market Closed? Holidays & Early Closes
When is the US stock market closed? Every upcoming market holiday and 1:00 p.m. early-close day from the live exchange calendar, cross-checked on the tape.
Why Short Interest Data Is Always Two Weeks Old
Short interest is measured twice a month and published 10-45 days later. The receipts: ten settlements, their arrival dates, and the missing June print.
How Do Market Makers Make Money? Real Spread Data
What market makers do and how they earn the bid-ask spread — with real tick data: measured spreads, quote updates per second, and the SQL behind every number.
What Is a Bid-Ask Spread? Real Costs, Real Market Data
Learn what a bid-ask spread is, how to calculate it, and what it costs per trade — with real spreads measured from tick-level quote data on US stocks.
What Is the 2s10s Spread? The Yield Curve in Real Data
What the 2s10s spread is, how the Treasury yield curve works, and what past inversions looked like — every chart built from auditable market data.
Short Interest vs. Short Volume: What Each One Measures
Short interest and daily short volume measure different things. See real per-ticker numbers, days-to-cover math, and the exact query behind every figure.
What Is an Ex-Dividend Date? Dividend Dates Explained
Declaration, ex-dividend, record, and payment dates explained with real timelines from thousands of US stocks. See who gets the dividend and when.