The tendency of stocks to perform better in December than in any other month of the year. This may be because of increased sales and earnings due to the Christmas season, or because of expectations for new products at the start of the next year. In any case, December has usually, historically, been the best month for stock performance. It is also noteworthy that, in general, fewer bankruptcies are filed in December. See also: Monday effect.
The tendency of stock prices to move upward during the last month of the year. Historical statistics indicate December is the strongest month of the year for stock prices.