# What would be the largest single day gain the Dow could post? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 27, 2007, 1:54pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861 "2007-04-27T13:54:51Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![FlippyFly](https://avatars.discourse-cdn.com/v4/letter/f/e95f7d/32.png) [@FlippyFly](https://boards.straightdope.com/u/FlippyFly)\ **Post date:** [April 27, 2007, 1:54pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861/1 "2007-04-27T13:54:51Z")
What would be the largest single day gain the Dow could post? I don’t think there is any actual upper limit… so lets say everything came up right… inflation, jobs, earnings, politics, war, everything. At its current level, what is the largest single day gain we could see? 500 points? 1,000 points? At what level would they (if at all) close down the exchange? What about on the down side, how much could it lose in one day? ---
**Author:** ![Alwrong](https://avatars.discourse-cdn.com/v4/letter/a/94ad74/32.png) [@Alwrong](https://boards.straightdope.com/u/Alwrong)\ **Post date:** [April 27, 2007, 2:02pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861/2 "2007-04-27T14:02:53Z")
Well, let’s look at what has actually happened: > [@](#): > > 16 March 2000 > In days of high volatility, the Dow Jones posts its biggest single day points gain in history, gaining 499.19 points or just under 5% to close at 10630.60 > > 14 April 2000 > Biggest points loss in history, with the Dow shedding 617.78 points or 5.66% to close at 10305.77 From [BBC NEWS | Business | Dow Jones milestones](http://news.bbc.co.uk/1/hi/business/business_basics/145986.stm) Confirmed by this: [The day in numbers: 12,011.73 - CNN.com](http://edition.cnn.com/2006/BUSINESS/10/20/daynumbers.dowjones/index.html) ---
**Author:** ![Lunar\_Saltlick](https://avatars.discourse-cdn.com/v4/letter/l/977dab/32.png) [@Lunar\_Saltlick](https://boards.straightdope.com/u/Lunar_Saltlick)\ **Post date:** [April 27, 2007, 3:31pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861/3 "2007-04-27T15:31:39Z")
Percentages are more interesting. On one day in October 1987, the Dow plunged about 22%. It was something like 500 points. If it happened today, 22% would be somwhere in the vicinity of 2500 points. ---
**Author:** ![Lunar\_Saltlick](https://avatars.discourse-cdn.com/v4/letter/l/977dab/32.png) [@Lunar\_Saltlick](https://boards.straightdope.com/u/Lunar_Saltlick)\ **Post date:** [April 27, 2007, 3:39pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861/4 "2007-04-27T15:39:19Z")
According to Wikipedia, the largest one-day percentage gain was 15.3% in the 1930s. Today, 15% would give somewhere around 1900 points. Big one-day gains seem to happen pretty frequently after big drops, when the bargain hunters come looking. ---
**Author:** ![dalej42](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dalej42](https://boards.straightdope.com/u/dalej42)\ **Post date:** [April 27, 2007, 7:02pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861/5 "2007-04-27T19:02:45Z")
[Here](http://www.nyse.com/press/circuit_breakers.html) is the information on the “circuit breakers” the NYSE will use in the event of a large drop in the Dow. ---
**Author:** ![T\_SQUARE](https://avatars.discourse-cdn.com/v4/letter/t/9de053/32.png) [@T\_SQUARE](https://boards.straightdope.com/u/T_SQUARE)\ **Post date:** [April 27, 2007, 11:32pm UTC](https://boards.straightdope.com/t/what-would-be-the-largest-single-day-gain-the-dow-could-post/401861/6 "2007-04-27T23:32:06Z")
I’m sure it’s been done, but you could plot the distribution and calculate probabilities of a given movement. It’s not normal, as markets have momentum, so it will have heavy tails. I think the Dow moved over 20 standard deviations in one day once; if normally distributed, such an outcome would still be unlikely if the NYMEX was open every day since the big bang, or something ridiculous like that. This is just my recollection, I could be full of shit.