Stock market cycles are the long-term price patterns of the stock market.
There are many types of business cycle

Business cycle

The term business cycle refers to economy-wide fluctuations in production or economic activity over several months or years...

s including those that impact the 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...

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In his book The Next Great Bubble Boom, Harry S. Dent Jr., a Harvard graduate and Fortune 100 consultant, outlines several cycles that have specific relevance to the stock market. Some of these cycles have been quantitatively examined for statistical significance.

The major cycles of the stock market include:

• The four-year presidential cycle in the USA.
• Annual seasonality
  Seasonality
  In statistics, many time series exhibit cyclic variation known as seasonality, periodic variation, or periodic fluctuations. This variation can be either regular or semi regular....
  
  , in the USA and other countries.
• "The Halloween indicator
  Halloween indicator
  The Halloween indicator is a variant of the stock market adage "Sell in May and go away," the belief that the period from November to April inclusive has significantly stronger growth on average than the other months. In such strategies, stocks are sold at the start of May and the proceeds held in...
  
  " (or "Sell in May and Go Away")
• The "January effect
  January effect
  The January effect is a calendar-related anomaly in the financial market where financial security prices increase in the month of January. This creates an opportunity for investors to buy stock for lower prices before January and sell them after their value increases.Therefore, the main...
  
  "
• The lunar cycle

Investment advisor Mark Hulbert has tracked the long term performance of Norman Fosback’s a Seasonality Timing System that combines month-end and holiday-based buy/sell rules.