Santa Claus Rally

A Santa Claus rally is a late-December rise in stock market activity, generally seen over the final week of trading prior to the new year. The rally is generally attributed to anticipation of the January effect, an injection of additional funds into the market, and to additional trades which must, for accounting and tax reasons, be completed by the end of the year. The Santa Claus rally is also known as the December Effect.
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Seasonal rise in stock prices in the last week of the calendar year, between Christmas and New Year's day.