If one wants to see how often in the past the NASDAQ was down from the year before and was down a year later, the correct method is take every trading day that is down from the year before ( 252 trading days ), not just the last trading day of the year.
First, a disclaimer;
stationarity is one of the most important concepts in probability and statistics
the essence of its meaning is that the specific pattern you are trying to understand is constant in a probabilistic sense
technically, its unconditional joint probability distribution does not shift over time.
in blackjack, the rules of the game are known and constant, and based on
the cards seen so far we can know the probabilities of the outcomes of
the next hand.
in finance, the underlying structure of the world is complex, unknown,
and changes over time. there is little in the way of objective, certain
truth. any historical data analysis assuming otherwise under-states the
uncertainty around forward looking forecasts. ( Benn Eifert )
Looking at the past, up to 1/25/2024, the NASDAQ will be lower 24.59% from a year ( 252 trading days ) earlier. The following year it is lower 28.6% of the time. If the Index is higher from a year earlier, the following year is down 23.92% of the time. A down year has been followed by a down year more often than an up year is followed by a down year.