Curriculum·S201 Market Structure and Price Formation·about 41 min
Order books
By the end of this lesson you can
- →Read a book as inventory at prices rather than as a price, and estimate the fill of a given size
- →Explain why displayed depth is an offer that can be withdrawn, not a commitment
- →Compute the notional required to move a book by a stated percentage, and invert it to size a position
- →Identify the conditions under which depth disappears precisely when it is needed
Sophomore · enrolled learners
This lesson opens with The liquidation cascade of 10 October 2025.
- What happened
- Following an announcement of new tariffs on Chinese imports, crypto markets sold off into open interest that stood near a record $217B. More than $19B of leverage was liquidated in roughly a day, the largest single-day deleveraging event recorded. Of $9.89B in forced liquidations, about 70 percent occurred inside 40 minutes, at a rate reported as 14.6 times the surrounding periods, with a peak minute of $3.21B of which 93.5 percent was forced selling. More than 1.6 million trader accounts were affected. Bitcoin fell over 14 percent toward $104,000 and ether more than 20 percent to around $3,500. Liquidity providers and market makers withdrew during the event, widening spreads and draining the books further.
- The decision point
- Every position that liquidated had been sized against depth that was visible on a screen beforehand. That depth was an offer, not a commitment, and the parties posting it are under no obligation to keep it there. The books were thinnest at the exact moment the largest volume needed to cross them, because the same conditions that produce forced selling also cause market makers to step away.
- Recorded loss
- $19,000,000,000
What you will be able to answer
- →What is an order book?
- →Is displayed depth a commitment?
- →What did 10 October 2025 demonstrate about depth?
- →How do you size a position against a book?
Orientation and Year One are open: anyone can read them without an account. From Year Two onward the lessons are for enrolled learners, because progress through the later years only means anything if it is tracked against a record.
It is free. We do not sell the list and there is nothing to buy at the end of it.
Sources and review
- https://www.coindesk.com/research/market-spotlight-the-19-billion-liquidation-that-shook-crypto
- https://www.coingecko.com/learn/october-10-crypto-crash-explained
- https://www.fticonsulting.com/insights/articles/crypto-crash-october-2025-leverage-met-liquidity
- https://www.sec.gov/newsroom/press-releases/2023-13
Confidence high·Volatility medium·Reviewed 2026-08-05·Owner unassigned
Contested
Liquidation totals for 10 October 2025 vary between roughly $19B and higher figures depending on the venues counted and on how exchanges report partial liquidations, and it is widely accepted that reported figures understate reality because several venues throttle their liquidation feeds. Treat $19B as a reported floor with its source attached.
The tariff announcement is the widely reported trigger, and a trigger is not a cause. The condition that made a cascade possible was record open interest against finite depth, which would have been true of any sufficiently large shock. Do not let a revision present the news event as the explanation.