Study: why you shouldn't sell in May and go away

The stock market actually goes up more often than it goes down from May - October.

The stock market has a 50-50 chance of going up from May - September

https://bullmarkets.co/study-why-you-shouldnt-sell-in-may-and-go-away/

 

Over the last 10 years you are right.

 

50-50 sounds OK. But, only 50-50? Maybe, given the inherent upward bias of stock indices 50-50 isn't so good?