Santa Claus rally
From ACT Wiki
Behavioural economics - technical analysis - calendar effects.
The theory that equity prices and other traded asset prices have a tendency to rise in the last trading week of December, and the first two trading days in January.
The Santa Claus rally is one of a number of behavioural calendar effects in market prices.
There is a range of opinion about the possible causes of calendar effects, and about the existence of calendar effects.