How Options Are Quoted in Volatility
Institutions trade options quoted in volatility rather than in dollars. See what a vol quote looks like and how it turns into a cash price at execution.
Market structure
How US equity markets actually move orders, form prices, and print trades: auctions, spreads, venues, and the plumbing underneath, each explained with real market data.
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How to Become a Registered Market Maker
How to become a market maker: exchange registration, two sided quoting size and width rules, net capital under Rule 15c3-1, and what suspension means.
NYSE Parity and D-Quotes: How Fills Allocate
NYSE parity splits a fill across participants at the same price, so a floor broker can trade ahead of an earlier public order. See the allocation math.
Why Crypto Has No NBBO: No SIP, No Tape
Crypto has no NBBO: no SIP, no consolidated tape. Why two venues show different prices at the same instant, and what index and reference rates fill in.
Self-Match Prevention and Wash Trades
Self-match prevention stops your own two orders from trading with each other. How SMP works inside the matching engine, and where wash trade law begins.
Quote-Driven vs Order-Driven Markets
Quote-driven vs order-driven markets, defined plainly, plus the hybrid reality of US equity trading and what depth each structure actually shows you.
Why Trading Volume Dies at Midday: U-Shape
Trading volume dies at midday in a U shaped curve: heavy at the open and close, thin from 11:30 to 14:00 ET. See the intraday profile and what it costs.
Maker-Taker Fees and Rebates Explained
Maker-taker fees explained with arithmetic: what a venue keeps between the taker fee and the maker rebate, and how that gap steers where brokers route orders.
SIP Feeds vs Direct Exchange Feeds
Why two screens show different prices for the same stock: what the SIP consolidated tape carries, and where direct exchange feeds gain speed and depth.
Price-Time Priority vs Pro-Rata Fills
Why two orders at the same price get different fills: price-time priority, pro-rata and parity allocation, worked through one book with real market data.
Why Stocks Halt: Limit Up-Limit Down Bands
Why do stocks halt? Limit up-limit down bands pause trading for five minutes when price runs past a rolling reference. Here is the machinery, with data.
Iceberg Orders Explained: Hidden Liquidity
What is an iceberg order? How the displayed slice and hidden reserve work, why each refresh loses queue priority, and what the pattern looks like on the tape.
Market Recap: July 30, 2026, The Day in Numbers
July 30, 2026, measured from the tape: index scoreboard, breadth, sector spread, options flow, the quote tape, rates and calendar, every figure query-backed.
Market Recap: July 28, 2026, The Day in Numbers
July 28, 2026, measured from the tape: index scoreboard, breadth, sector spread, options flow, the quote tape, rates and calendar, every figure query-backed.
Market Recap: July 27, 2026, The Day in Numbers
July 27, 2026, measured from the tape: scoreboard, breadth, sector spread, options flow, the quote tape, rates and the calendar, every figure query-backed.
Market Recap: July 29, 2026, The Day in Numbers
July 29, 2026, measured from the tape: index scoreboard, breadth, sector spread, options flow, the quote tape, rates and calendar, every figure query-backed.
What Is Gamma Exposure (GEX)? Dealer Hedging
Gamma exposure, or GEX, estimates the hedging dealers do as prices move. See the calculation, the assumptions it rests on, and why free GEX numbers differ.
Does Dividend Capture Actually Work?
Dividend capture buys before the ex dividend date and sells after. See how far prices really open down, and what stacks up against the dividend collected.
What Is Max Pain in Options? The Real Math
Max pain is the strike where option holders collect the least at expiry. See the calculation on a real SPY chain and how close settlement actually landed.
Market Recap: Week of July 20, 2026
The week after July's monthly options expiration, measured: the index scoreboard, sector dispersion, weekly breadth, and where the tape's dollars went.
Unusual Options Activity: Last Session
Unusual options activity ranked from the full US options tape: which underlyings traded far above their own 20-session average, and how calls and puts split.
Which Stocks Have Daily Options?
SPY, QQQ and IWM list a new options expiration every trading day, and the index roots go deeper. See which tickers carry dailies and which only get Fridays.
How Leveraged ETFs Work (and Why They Decay)
How 3x leveraged ETFs like SOXL actually work, why they can beat or lag their multiple over time, and why inverse funds such as SOXS keep reverse-splitting.
Unusual Volume Stocks This Week, Measured
Unusual volume stocks this week, ranked: trailing-week turnover vs. each name's prior 40 sessions, with weekly returns, rarity context and persistence.
When Do 0DTE Options Trade? By the Hour
0DTE options trade heaviest in the morning, not at the close: hourly volume, the calls-vs-puts clock, weekday shares and same-day spreads, all measured.
What Is Average Daily Volume (ADV)?
Average daily volume is a stock's typical shares traded per day. It is the denominator inside days to cover, relative volume, and every liquidity screen.
IPO Lockup Expiration: Meaning & Release Date
A lockup expiry is the day IPO insiders can finally sell, customarily 180 days after listing. Where to find the exact end date, and how five unlocks traded.
The 2010 Flash Crash, Minute by Minute
May 6, 2010: about a trillion dollars of market value vanished and mostly returned inside 36 minutes. The minute tape of the flash crash, receipted.
What Is a Short Squeeze? GameStop, Measured
A short squeeze is a rally that feeds on short sellers buying to close. GameStop's 2021 records, short interest, days to cover and price, tell it in numbers.
What Is the Put-Call Ratio? A Data Guide
The put-call ratio is puts traded divided by calls traded. See its real range on the full US options tape: by expiration, index vs equity, and against a decade.
What Is Triple Witching? Volume & Volatility
Triple witching is the quarterly session when index futures, index options and stock options expire together. Volume and volatility, measured on the real tape.
When Do Options Expire? Friday 4 PM ET & Daily
Most options stop trading at the 4:00 PM ET close on expiration Friday; weeklies expire Fridays, monthlies the third Friday, and SPY and QQQ expire daily.
Why Do Stocks Gap Up or Down Overnight?
A gap up or gap down is the distance from the prior close to the 9:30 open, after 17.5 closed hours. SPY overnight gap size, Mondays widest, plus stop risk.
What Is Days to Cover? Short Interest Ratio
Days to cover, the short interest ratio, is shares short divided by daily volume: how many days the exit would take. Real settlement data shows what is high.
What Is a Stock Split? Ratios and Mechanics
A stock split multiplies share count and divides price, value unchanged. Real split records show which ratios companies pick, and what prices did next.
Market Recap: Week of July 6, 2026
A chip rout, a bounce, the summer's wildest open, and NVDA's Friday, netting out to a quiet index week where most stocks fell and MU out-traded SPY itself.
Market Recap: July 10, 2026, The Day in Numbers
NVDA woke up and led the whole tape a day after sitting out. META doubled down, MU cooled, small caps slipped, and the index barely moved. Friday in numbers.
Market Order vs Limit Order, Measured
A market order fills now at the best available price; a limit order caps your price but may not fill. Real quote data shows what each choice costs in dollars.
Market Recap: July 9, 2026, The Day in Numbers
Chip equipment gapped up hard and faded, mega-caps gapped down and ripped back, the tape flipped decisively green, and NVDA sat it out, closing red.
SPCX: SpaceX Stock Price Decline From Peak
How far SpaceX stock (SPCX) sits below its June 16, 2026 peak, measured to the latest close: the session path, spreads, options flow, and SEC filings.
How Much Does It Cost to Trade Options?
Options commissions may be zero, but the bid-ask spread is real. See the median cost to trade SPY, QQQ, IWM, GLD, and TSLA options, in basis points.
Market Recap: July 8, 2026, The Day in Numbers
A one-day chip bounce the index barely felt: most semis green, NVDA up a second day, MU the heaviest dollar name, and a broad tape more than two-to-one red.
How Big Is the OPRA Options Quote Feed?
How big is the options quote feed? We count one full day of OPRA-scale NBBO updates in our warehouse and measure it against the entire stock quote tape.
What It Costs to Trade a Stock, Measured
Commissions are zero, but every stock trade pays the bid-ask spread. See the real cost of trading stocks, measured in basis points across 12 household names.
What Is the NBBO? National Best Bid and Offer
The NBBO is the national best bid and offer, the one consolidated stock quote your broker must match or beat. See how fast it updates, from real tick data.
What Is FINRA Short Interest? Days to Cover
FINRA short interest is shares sold short and not yet bought back. See how it's reported twice monthly, settlement dates, days to cover and percent of float.
What Is a Reverse Stock Split? Good or Bad?
A 1-for-10 reverse stock split turns 10 shares into 1 at ten times the price, position value unchanged. Neutral arithmetic; the companies that use it are not.
Locked and Crossed Markets, Explained With Data
A locked market quotes the bid equal to the ask; a crossed market quotes the bid above it. See why Reg NMS bans both and how often each hits the tape.
Why Are Spreads Wider at the Open? Real Data
Why are spreads wider at the open? Tick-level quotes price the opening premium half hour by half hour, show how fast it fades, and what premarket really costs.
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.
What Is Dark Pool Trading? FINRA Volume Data
Dark pool trading matches stock orders with no displayed quotes. Every fill prints to the FINRA tape, the measured off-exchange share of five liquid stocks.
Stock Float vs. Shares Outstanding Explained
A stock's float is the shares free to trade, shares outstanding minus locked-up insider stock. See what counts as a low float and how thin floats trade.
What Is a Block Trade? Big Prints & the Data
What a block trade is, where the 10,000-share / $200,000 rule comes from, and how big prints reach the tape, dark pools, exchanges, on real block-trade data.
Market Recap: July 7, 2026, The Day in Numbers
A semiconductor break the index barely felt: chips down hard, NVDA green through it, a two-to-one red tape, and SPY quoting its tightest spread in a month.
SpaceX Joins the Nasdaq-100: The Index-Add Trade
SpaceX's fast-tracked Nasdaq-100 add and the giant closing auction that priced it: Matt Levine's account, verified and extended on our own tick tape.
What Is RVOL (Relative Volume)? How to Read It
RVOL (relative volume) is a stock's volume ÷ its 20-day average: above 1 is busier-than-usual trading. Plus intraday time-of-day RVOL and what counts as high.
What Is VWAP? Volume-Weighted Average Price
VWAP stands for volume-weighted average price. Definition: price times volume divided by total volume, reset daily. What it means on a real trading day.
What Is the Closing Auction? (Closing Cross)
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.
Market Recap: July 6, 2026, The Day in Numbers
Back from the Independence Day break: a growth-led gap up, a sector split several times the index move, a reverse-split wall, the month's tightest quotes.
Market Recap: July 2, 2026, The Day in Numbers
Holiday-eve rotation: green breadth under a falling Nasdaq, tech last of the eleven sector funds, memory-rout day two, and the split that faked a crash.
What Is a Bid-Ask Spread? Real Costs
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.
How Do Market Makers Make Money? The Spread
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.
Market Recap: July 1, 2026, The Day in Numbers
The second half opened quiet at the index and violent underneath: the memory complex broke, META jumped, and most S&P sectors still closed green.
Market Recap: June 30, 2026, The Day in Numbers
The quarter's last session in numbers: a technology-led index gain over a mostly red tape, the memory complex on top, and a same-day options tape at the close.
Market Recap: June 29, 2026, The Day in Numbers
June 29, 2026 in numbers: a growth-led index gain, a four-point sector spread, a memory-stock round trip, the 0DTE tape, penny-tight quotes and rates.