What Is 0DTE Options Trading? Measured on Tape
0DTE options expire the same day they trade. What zero days to expiration means, which tickers expire daily, and the measured same-day share of options volume.
Learn
Evergreen explainers of how US markets actually work — each concept taught with real, queryable market data.
Options Volume vs. Open Interest, Explained
Volume counts contracts traded today; open interest counts contracts still outstanding. Both defined, plus one full day of the US options tape, measured.
What Is a Stock Float? Float vs. Outstanding
A stock's float is the share count actually free to trade. How float differs from shares outstanding and authorized shares, and what IPOs float at listing.
What Is a Reverse Stock Split? Real Examples
What a reverse stock split is, how the share math works, what happens to fractional shares, and real examples measured from 2026's split records.
What Is Dark Pool Trading? Off-Exchange Volume
What dark pool trading is, why big orders go off-exchange, and how every dark-pool trade still prints to the public tape through FINRA reporting.
What Is a Block Trade? Big Prints, Explained
What a block trade is, where the classic 10,000-share / $200,000 definition comes from, and how big institutional prints reach the tape — on real tick data.
What Is the Opening Auction? How Stocks Open
What the opening auction is, how one 9:30 a.m. cross sets each stock's official opening price, and why the open can differ from the first trade of the day.
Stock Market Hours: When Markets Open & Close
What time does the stock market open and close? Regular hours run 9:30 a.m. to 4:00 p.m. ET, premarket from 4:00 a.m., after-hours to 8:00 p.m. On tape data.
What Is Short Interest? A Data-Backed Guide
Short interest is the count of shares sold short and not yet bought back. See how FINRA measures it twice a month, days to cover, and what counts as high.
Record Date vs. Ex-Dividend Date: What Changed
Record date vs. ex-dividend date: since the T+1 settlement switch in May 2024 they fall on the same day for nearly every US dividend. The change, measured.
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 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.
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.
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 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.
Stock Market Holidays 2026–2027: NYSE & Nasdaq
When is the stock market closed? Every upcoming NYSE & Nasdaq holiday and 1:00 p.m. early close for 2026–2027, from the live exchange calendar.
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.
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 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.
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.
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.