Curriculum·R403 Risk Management as the Actual Product·about 42 min
Drawdown, streaks, and ruin
By the end of this lesson you can
- →Compute the gain required to recover any drawdown, and why it is not symmetric
- →Estimate the longest losing streak you should expect from your win rate and trade count
- →Combine streak length and risk per trade into an expected worst drawdown
- →Distinguish mathematical ruin from the practical ruin that arrives much earlier
Senior · enrolled learners
This lesson opens with Melvin Capital, January 2021 to May 2022.
- What happened
- Melvin Capital began 2021 with about $12.5B under management. Its short positions in heavily shorted equities, most prominently GameStop, were the target of a coordinated buying campaign in January 2021, and the fund reported a loss of about 53 percent for the month. During the episode Citadel and Point72 supplied a combined $2.75B of fresh capital, and the fund held a little over $8B at the end of January including that injection. It closed the relevant short position. The fund was reported down about 46 percent for the first half of 2021 and about 39 percent for the full year. On 18 May 2022 its founder wrote to investors that the appropriate step was to wind down the funds, liquidate and return cash.
- The decision point
- The fund survived the event. It closed the position, took an emergency capital injection, and traded for sixteen more months without a comparable single loss. It still wound down, because a drawdown of that size does not require you to be wrong again, it requires you to be right by more than twice as much as you were wrong, for long enough that the people funding you wait. Recovery is not the inverse of the loss and it is not the only thing that has to survive the loss.
- Recorded loss
- $6,000,000,000
What you will be able to answer
- →What gain recovers a drawdown of d?
- →How long a losing streak should you expect?
- →What does that streak cost?
- →What is practical ruin?
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.cnbc.com/2021/01/31/melvin-capital-lost-more-than-50percent-after-betting-against-gamestop-wsj.html
- https://www.cnn.com/2022/05/19/investing/melvin-capital-hedge-fund-closes/index.html
- https://www.benzinga.com/news/21/07/21909875/gamestop-short-seller-melvin-capital-ended-2021-first-half-with-46-loss-report
- https://en.wikipedia.org/wiki/Melvin_Capital
Confidence medium·Volatility low·Reviewed 2026-08-07·Owner unassigned
Contested
Melvin's January 2021 loss is reported at 53 percent and at more than 50 percent depending on the source, and the composition of the roughly $8B at month end relative to the $2.75B injection is a matter of reporting rather than a published breakdown. Part two treats the injection arithmetic as derived and labels it as such.
The expected longest streak formula in part three is a standard approximation for independent trials and real trade outcomes are not independent, being clustered by market regime. Clustering makes streaks longer than the formula predicts, so the estimate is a floor rather than a central case.
S207-02 owns sizing against a distribution at Sophomore level. This lesson owns the drawdown and streak arithmetic that produces the distribution. R403-L runs it on the learner's own parameters. Keep the split.