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's executive summary said the initial decline 'ignited mechanical price-insensitive selling by a number of institutions employing portfolio insurance strategies and a small number of mutual fund groups reacting to redemptions.' By its estimate, sell programs by three portfolio insurers accounted for just under $2B of the day's just under $21B of NYSE sales, and in the futures market portfolio insurer sales amounted to the equivalent of about $4B of stock, roughly 34,500 contracts, being over 40 percent of futures volume excluding locals' transactions.
- 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.berkshirehathaway.com/letters/1987.html
- https://www.federalreservehistory.org/essays/stock-market-crash-of-1987
Confidence high·Volatility low·Reviewed 2026-08-07·Owner unassigned
Contested
How much of the 1987 decline portfolio insurance caused is genuinely contested, and the regulators of the day disagreed. The Brady Commission assigned it a central amplifying role, and the SEC report described ways it may have harmed the market. The CME's Committee of Inquiry said it 'did contribute significantly to selling in the futures markets' but was 'only one of many sources of selling, and does not by itself explain the magnitude of the crash', and the acting chairman of the CFTC said the trading patterns in the CFTC's data did not correspond with the cascade theory. All three are quoted in Carlson's Federal Reserve working paper (FEDS 2007-13). 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.
The $60B to $90B is the Brady Report's figure for equities under portfolio insurance in mid-October 1987, as quoted in Berkshire Hathaway's 1987 letter; other estimates differ with the definition, so the range is stated rather than a point figure. The Brady Commission's executive-summary words and the selling shares are the Brady Report's as quoted by Shiller (NBER Macroeconomics Annual 1988, citing Brady p. 36), where the over 40 percent excludes locals' transactions; Carlson's paper puts it at roughly 40 percent of non-market-maker futures sales, citing the same page. The 508 points and 22.6 percent are from the Federal Reserve History essay on the crash.
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.