Black Monday 1987: the one-day stock market crash

What happened on Black Monday 1987?

Black Monday fell on 19 October 1987. The Dow Jones Industrial Average opened at 2,246.74 and closed at 1,738.74, a loss of 508 points. Selling arrived from the first minutes and kept growing through the session. Orders piled up faster than exchanges could process them, and some investors waited an hour or more for confirmation of their trades. The day ranks as the largest one-day percentage fall in the history of the Dow.

The setup began the week before. On 14 October a trade deficit figure higher than expected pushed the dollar and share prices down, and interest rates rose. The pressure built into the weekend, and Monday opened with a wave of sell orders from institutions and individuals alike, which met a market built for far smaller volumes.

How big was the Black Monday 1987 stock market crash?

The Dow lost 22.6% in one session, and the S&P 500 lost 20.47%. Both figures dwarf the daily moves investors normally see. Of 2,257 NYSE-listed stocks, 195 faced trading delays or halts, and computer and communication systems were overwhelmed. A fall of this size in 1 day leaves investors almost no time to adjust their positions.

Worldwide losses were estimated at $1.71 trillion. The Brady Commission report recorded margin calls about 10 times their average size and 3 times the previous highs, and 11 firms received margin calls larger than their adjusted net capital. These numbers show how borrowed money turned a price fall into a funding problem within hours.

Which markets joined the 1987 stock market crash?

Black Monday spread around the world. Tokyo fell 14.9% in a single day, and Japanese losses reached $421 billion. The FTSE 100 fell 14% by midday on the day it reopened and reached a trough 36% below its peak in mid-November. Of 23 major markets, 19 fell more than 20%, and Austria was least affected with a fall of 11.4% in US dollar terms.

Hong Kong shows how local choices shaped the outcome. The stock exchange and futures exchange committees announced a closure for the next morning, and the closure lasted 4 working days. New Zealand fell nearly 15% on the first day and had lost 60% by its February 1988 trough. Closing a market stops the selling, and it also keeps investors away from their own money.

Why did the stock market crash on Black Monday 1987?

Several forces met in October 1987. International investors had pushed US share prices higher through the 1980s, and valuations stood well above the postwar average: the S&P 500 traded at 23 times earnings, against an average of 14.5. A large trade deficit weighed on the dollar. A full ranking of these forces sits on the page that explains what caused the 1987 stock market crash.

Market structure made the fall steeper. The Federal Reserve describes mismatched clearing and settlement timelines for stocks versus options and futures, and exchanges with limited ability to step in during large sell-offs. Program trading, including index arbitrage, carried selling pressure from the futures market into the stock market. Each mechanism turned a price drop into more selling, the feedback loop that defines a crash.

What role did portfolio insurance play on Black Monday 1987?

Portfolio insurance was a hedging technique that institutional investors used in the 1980s. It relies on futures and options to offset price moves, and computer models told the user to sell index futures as prices fell. When many users followed the same rule on the same day, their selling met a thin market. The Federal Reserve notes that the strategy accelerated the crash because early losses triggered further rounds of selling.

Researchers still debate how large the effect was. Hayne Leland argues the price impact was probably small, and a Chicago Mercantile Exchange report found that other investors carried 3 to 5 times more influence than portfolio insurers. The page on portfolio insurance and the 1987 crash lays out the mechanics and the evidence on both sides.

How did regulators answer the 1987 stock market crash?

On 20 October 1987 Fed Chairman Alan Greenspan affirmed the Fed’s readiness to serve as a source of liquidity to support the economic and financial system. Behind the scenes the Fed encouraged banks to keep lending on their usual terms, and it injected $17 billion into the banking system that day. The market rallied on 20 October, and credit kept flowing.

Regulators then rebuilt market plumbing. Circuit breakers arrived after the crash so that exchanges could halt trading during sharp declines. Under current NYSE rules, trading halts when the S&P 500 falls 7%, 13% and 20%. The 2020 fall triggered these halts 4 times in 1 week, which shows that the 1987 design still shapes how markets handle stress.

What can investors learn from Black Monday 1987 today?

3 lessons stand out. Borrowed money turns a price fall into forced selling within hours. Rules that sell automatically can push many investors in the same direction at once. Liquidity can vanish on the day you need it, so a plan that relies on selling at a fair price in a crash needs a margin for error. As of October 2026 these lessons remain a practical checklist.

Recovery matters as much as the fall. The S&P 500 dropped to 230.30 by November 1987, a 31.6% fall from its peak, and regained its pre-crash high of 336.77 on 26 July 1989, about 21 months after the crash. EQOS Asia turns lessons like these into a repeatable score, described on the EQOS Asia method page. This page is general information, not investment advice.

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About the author

Stéphane Jambu

President, EQOS Forecast Asia

Stéphane Jambu leads EQOS Forecast Asia and works as a consultant in e-commerce, search visibility, and AI. LinkedIn profile