Greetings, I am new to investing well im just reading about stocks and etc.

My questions may sound dumb, but I am confused
I know stocks rise when people buy, and fall when people sell.

But if one person buys 100,000 shares of a stock, will that stock price rise dramatically from that person buying the 100,000 shares?



I think a good example will be if an investor bought 500,000 shares of apple when it was starting to go up, who bought the shares priced at $199.25
Apple's stock (AAPL) keeps going up (now 355.65).

So if that investor was to sell all his 500,000 shares of stock, then would apple's price drop?

Does this also go the same if the majority stock holder was to sell most of his shares as well?