Curriculum·R406 Options and Structured Positions·about 32 min
Options fundamentals
By the end of this lesson you can
- →State the four things that define any option contract
- →Explain the difference between buying an option and replicating one
- →Compute what replication costs when the market gaps
- →Identify which side of an option position is an obligation, and price it accordingly
Senior · enrolled learners
This lesson opens with Portfolio insurance and 19 October 1987.
- What happened
- Portfolio insurance was a technique for replicating a protective put without buying one, by selling index futures as the market fell and buying them back as it rose, in proportion to the option's changing delta. By October 1987 an estimated $60B to $90B of equity assets were being dynamically hedged this way. On 19 October the Dow Jones Industrial Average fell 508 points, or 22.6 percent, in a single session. The Brady Commission found that the technique and its interaction with the stock index futures market amplified the decline. Sell programs by three portfolio insurers accounted for just under $2B of the day's slightly under $21B of NYSE sales, and in the futures market portfolio insurer selling amounted to the equivalent of about $4B of stock, roughly 34,500 contracts, being over 40 percent of futures volume.
- The decision point
- A bought put requires the holder to do nothing at all once it is paid for. A replicated put requires the holder to trade, continuously, in the direction the market is already moving, and the strategy therefore stops working in exactly the conditions it was purchased to survive. The premium on a real option is the price of not having to be present, and portfolio insurance was an attempt to avoid paying it.
What you will be able to answer
- →What defines an option contract?
- →Bought option or replicated one?
- →What does a gap cost a replication?
- →Which side is the obligation?
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.federalreserve.gov/pubs/feds/2007/200713/200713pap.pdf
- https://www.nber.org/system/files/chapters/c10958/c10958.pdf
- https://fee.org/articles/the-brady-report-threat-to-stock-market-stability/
- https://www.markethistories.com/en/black-monday-1987-the-day-the-machines-broke-the-market
Confidence high·Volatility low·Reviewed 2026-08-07·Owner unassigned
Contested
How much of the 1987 decline portfolio insurance caused is genuinely contested. The Brady Commission assigned it a central amplifying role, later academic work argued the technique was one contributor among several including valuation and macroeconomic conditions, and the counterfactual is unknowable. Per P6 this lesson relies only on the mechanism and the measured selling shares, both of which are documented, and does not claim it caused the crash.
Estimates of assets under dynamic hedging in 1987 range from about $60B to about $100B depending on the source and the definition. The range is stated rather than a point figure.
R401-01 owns the instrument taxonomy and established that a bought option's loss is its premium. This lesson owns option contract terms and the replication argument. Keep the split.