Black Monday 1987
On Monday, October 19, 1987, the Dow Jones Industrial Average fell 508 points, a decline of 22.6% in a single trading session. It remains the largest one-day percentage decline in the Dow's history, more than double the 12.8% drop on Black Monday of 1929. The S&P 500 fell 20.5%. In dollar terms, approximately $500 billion in market capitalization was destroyed in six and a half hours.
The crash came without an obvious fundamental trigger. There was no war, no pandemic, no bankruptcy of a major financial institution, and no economic recession underway. The economy was growing. Corporate earnings were solid. Yet the stock market experienced its worst single day ever. The episode challenged the efficient market hypothesis, raised fundamental questions about the stability of electronic trading systems, and demonstrated that modern financial markets could produce dislocations of a speed and magnitude that few thought possible.
The Prelude
The stock market had been rising strongly since 1982. The Dow, which bottomed near 777 in August 1982, had risen to 2,722 by August 25, 1987, an increase of over 250%. The bull market was driven by falling interest rates, corporate restructuring, the leveraged buyout boom, and growing participation by institutional investors. By the summer of 1987, valuations were stretched. The S&P 500 traded at roughly 23 times earnings, well above historical averages.
The market peaked on August 25, 1987, and began to decline. Between August 25 and October 16 (the Friday before the crash), the Dow fell approximately 17%. Several specific events contributed to the growing unease.
The U.S. trade deficit, reported on October 14, was larger than expected, raising concerns about the value of the dollar and the potential need for higher interest rates to defend the currency. Treasury Secretary James Baker made public statements suggesting that the United States might allow the dollar to weaken, which alarmed foreign investors. Congress was debating legislation to eliminate tax benefits for financing corporate takeovers, which threatened the leveraged buyout activity that had been supporting stock prices.
On Friday, October 16, the Dow fell 108 points (4.6%), a significant decline that generated anxiety heading into the weekend. Over the weekend, investors had time to absorb the week's losses and decide what to do. Many decided to sell.
The Crash
The crash began in the Asian and European markets before U.S. markets opened. Hong Kong, Australia, and European bourses all experienced sharp declines. By the time the New York Stock Exchange opened at 9:30 a.m. Eastern time, a massive volume of sell orders had accumulated.
The opening was chaotic. Many stocks did not open on time because the specialists who made markets in individual stocks could not find enough buyers to match the flood of sell orders. By 10:00 a.m., stocks that had opened were already down sharply, and the S&P 500 futures market in Chicago was plunging.
The decline accelerated throughout the morning and into the afternoon. By the close, the Dow had fallen 508 points. Trading volume on the NYSE reached 604 million shares, roughly double the previous record. The ticker tape fell over two hours behind actual trading. Many investors did not learn the full extent of their losses until well after the market had closed.
The crash was not limited to the United States. Markets around the world experienced severe declines. Hong Kong fell 45.8% over October 19-26. Australia fell 41.8%. The United Kingdom fell 26.4%. Canada fell 22.5%. The crash was genuinely global, reflecting the interconnection of world financial markets.
Portfolio Insurance and the Cascade
The most widely cited contributor to the crash's severity was "portfolio insurance," a hedging strategy used by institutional investors. Portfolio insurance, developed by finance professors Hayne Leland and Mark Rubinstein, used a dynamic hedging strategy to provide downside protection for large stock portfolios. When stock prices fell, the strategy called for selling stock index futures to hedge the decline. When prices rose, the strategy called for buying futures to increase exposure.
In theory, portfolio insurance allowed large investors to participate in market gains while protecting against losses, similar to buying a put option. In practice, the strategy created a dangerous feedback loop. When prices declined, portfolio insurers sold futures. Their selling pushed futures prices lower, which triggered arbitrage selling in the cash market (index arbitrage programs sold the underlying stocks when futures were cheaper than the cash index). The selling in the cash market pushed stock prices lower, which triggered more futures selling by the portfolio insurers, which triggered more cash selling, and so on.
On October 19, portfolio insurance-driven selling accounted for an estimated $6 billion in S&P 500 futures sales, representing a significant fraction of total trading volume. The strategy, designed to protect individual portfolios against loss, created a cascade that magnified the market-wide decline far beyond what fundamental conditions warranted.
The irony was that portfolio insurance worked as designed for each individual user, but when many users employed the strategy simultaneously, their collective selling made the market decline worse for everyone. This is a classic example of a "fallacy of composition," where behavior that is rational for an individual is destructive when adopted by the group.
The Plumbing Nearly Failed
Beyond the portfolio insurance cascade, the crash exposed severe weaknesses in the operational infrastructure of financial markets.
Market makers withdrew. The specialists on the NYSE floor, who were obligated to maintain orderly markets by buying when others were selling, exhausted their capital within the first hour. Many effectively stopped making markets, leaving stocks without buyers.
The futures-cash link broke. Under normal conditions, the price of S&P 500 futures and the S&P 500 cash index track each other closely. On October 19, the futures market fell far faster than the cash market, with the discount reaching 20% or more at times. This dislocation meant that the normal arbitrage mechanism, which keeps the two markets aligned, broke down. Investors could not rely on the futures market to accurately signal the level of the cash market.
Margin and settlement systems were overwhelmed. The Chicago Mercantile Exchange, which cleared S&P 500 futures, faced an unprecedented volume of margin calls. Several major clearing firms were unable or unwilling to meet their obligations. The CME came within hours of a default that would have shut down the futures market entirely. A last-minute $400 million credit line from Continental Illinois bank (arranged through the Federal Reserve Bank of Chicago) prevented the default.
The phone system collapsed. In 1987, orders were placed by telephone. The surge in call volume overwhelmed the capacity of brokerage firms' phone systems. Many retail investors could not reach their brokers to place orders, either to sell or to buy.
The Fed's Response
Federal Reserve Chairman Alan Greenspan, who had been in office for only two months, issued a one-sentence statement before the market opened on Tuesday, October 20: "The Federal Reserve, consistent with its responsibilities as the nation's central bank, affirmed today its readiness to serve as a source of liquidity to support the economic and financial system."
The statement was brief but its message was clear: the Fed would provide whatever liquidity was needed to prevent the market crash from becoming a financial system collapse. Behind the scenes, the Fed aggressively injected reserves into the banking system through open market operations and encouraged banks to continue lending to securities firms and market makers.
The intervention worked. The market rallied 5.9% on Tuesday, October 20, and continued to recover over the following days. By early December, the market had recovered roughly half its Black Monday losses. By July 1989, the Dow had recovered to its pre-crash level. The economy did not enter a recession.
The speed and success of the Fed's response established a template that would be followed in subsequent crises. The Fed's willingness to act as a backstop for financial markets became an expectation among market participants, later crystallized as the "Greenspan put," the belief that the Fed would intervene to prevent catastrophic market declines.
What Caused It?
Nearly four decades later, there is no consensus on a single cause of the 1987 crash. The Brady Commission, appointed by President Reagan to investigate the crash, identified portfolio insurance and index arbitrage as amplifying mechanisms but acknowledged that they did not cause the initial decline. Academic research has explored multiple explanations.
Overvaluation. The market was expensive relative to earnings by August 1987. The 17% decline between August 25 and October 16 may have been a rational repricing that the crash of October 19 simply accelerated.
Interest rate fears. Rising bond yields in the weeks before the crash reduced the relative attractiveness of stocks. The 10-year Treasury yield had risen from about 7% in January to over 10% by October, a significant tightening of financial conditions.
Technical factors. Portfolio insurance, index arbitrage, and the limitations of market microstructure (the inability of specialists and market makers to absorb the selling) transformed what might have been an orderly decline into a disorderly rout.
International tensions. Trade deficit concerns, dollar weakness, and the Iran-Iraq War contributed to a general sense of geopolitical uncertainty.
The most honest assessment is that the crash resulted from the interaction of all these factors. The market was overvalued and vulnerable. A series of negative developments created selling pressure. The selling triggered portfolio insurance programs, which amplified the decline through a feedback loop. The operational limitations of the exchanges prevented the orderly matching of buyers and sellers. And the speed and magnitude of the decline itself generated panic among investors who had no algorithmic reason to sell but who were overwhelmed by the visual evidence that the market was collapsing.
Legacy
Black Monday changed financial markets in several lasting ways.
Circuit breakers. The NYSE implemented trading curbs that halt trading when markets decline by specified percentages. These circuit breakers, though they have been modified over the years, are designed to prevent the kind of uninterrupted cascading decline that occurred on October 19.
Risk management. The crash discredited portfolio insurance as a hedging strategy and prompted a broader rethinking of risk management practices. The recognition that strategies which work in isolation can be destabilizing when widely adopted was an important intellectual development.
Central bank doctrine. The Fed's successful intervention established the expectation that central banks would act aggressively to prevent market crashes from destabilizing the financial system. This expectation has been a factor in every subsequent crisis.
The market recovered. Perhaps the most important legacy of Black Monday, from an investor's perspective, is that the market recovered fully within two years and went on to one of the strongest bull markets in history during the 1990s. Investors who sold on October 19 or in the weeks that followed locked in devastating losses. Investors who held on, or who bought during the panic, earned extraordinary returns. The 1987 crash is one of the clearest demonstrations of the cost of panic selling and the value of a long-term perspective.
Put these principles into practice. Track fundamentals, build portfolios, and analyze stocks with AI-powered insights.
Start Free on GridOasis →