In some stock market

Stock market

A stock market or equity market is a public entity for the trading of company stock and derivatives at an agreed price; these are securities listed on a stock exchange as well as those only traded privately.The size of the world stock market was estimated at about $36.6 trillion...

s, the Mark Twain effect is the phenomenon of stock returns in October being lower than in other months. The name comes from the following quotation in Mark Twain

Mark Twain

Samuel Langhorne Clemens , better known by his pen name Mark Twain, was an American author and humorist...

's Pudd'nhead Wilson

Pudd'nhead Wilson

Pudd'nhead Wilson is a novel by Mark Twain. It was serialized in The Century Magazine , before being published as a novel in 1894.-Plot:...

: "October. This is one of the peculiarly dangerous months to speculate in stocks. The others are July, January, September, April, November, May, March, June, December, August, and February."

The 1929, 1987 and 2008 stock market crash

Stock market crash

A stock market crash is a sudden dramatic decline of stock prices across a significant cross-section of a stock market, resulting in a significant loss of paper wealth. Crashes are driven by panic as much as by underlying economic factors...

es roughly occurred in October.

Evidence in support of this effect was provided by Cadsby (1989) based on data on Canadian

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 stock market

Stock market

A stock market or equity market is a public entity for the trading of company stock and derivatives at an agreed price; these are securities listed on a stock exchange as well as those only traded privately.The size of the world stock market was estimated at about $36.6 trillion...

.