额。。。

如果你要出卖股票，现在股价10元，现在只能出售为10元。宣告股利后，额外加上1元收益了，只愿意11元或者更高出售；第二个问题涉及留存收益减少吧，具体忘了。

Firstly, the stock price might increase on the date when a firm make a announcemen to the public if investors view cash dividend as good news. The stock price rised from 10 to 11 and the cash dividend is 1, personally, this is coincident.
Secondly, the stock price will drop by the amount of cash dividend on the ex-dividend date because one day before the ex-dividend day, owners of the shares are entitled to obtain cash dividend, while on ex-dividend day, owners are not entitled to obtain cash dividend. So the difference between these two days should be the cash dividend theoretically (if we ignore other factors, such as taxes)

Hopefully it is useful!

股价的影响因素有很多 理论和现实差异比较大。第一个问题：宣告发放股利只是预期，宣告并没有导致公司现金流量的减少，反而在一定程度上说明公司发展趋势较好，有充足的现金和分红能力;第二个问题：股价并不是根据每股收益和市盈率相乘得出的，市盈率是股价每股股价除以每股收益，每股收益代表一定时期的值，股价基本每秒都在变，因此市盈率也是动态的，在逻辑上不能用市盈率乘以每股收益决定股价。粗浅之见，仅供参考

如果你要出卖股票，现在股价10元，现在只能出售为10元。宣告股利后，购买者实际支付的金额是股价+已宣告尚未支付的股利，所以股价会上升为11元。股利发放后，每股净资产减少，所以股价会下降。