New high before a holiday

Getting quite a few questions about this one today - is a new high before a holiday more likely to continue, or reverse, once traders return?

Since 1950, it was mostly positive.

Many of those gains, however, came between 1950 - 1960. From 1970 through the present, it's been less consistently positive.

When we zero in on the past 20 years, even less positive, at least in the very short-term.