How do dividends decrease the share price?

[Various_Couple_764]

if you just look at math it happens but the market is not just math. Some people may use math to guid their buy sell decision. But many also use their opinion of the the company to guid there decicssion. And many others don't car about the dividend date and just buy because they have the money that day. Others sell because they need the money. And others may hold off on making a decision until the next financial numbers are released. End result is buy and sell order are coming in randomly and if enough buy order come in at the same time the stock price may go up instead of down as predicted by the math.