Let us say, I join some company X. They offer me 400 stocks over 4 years of vesting period. Similar to me, there will be hundreds of employees who will be joining everyday.
Doing a quick Google search, Authorized and outstanding stocks are the common terms which I came across. So, let us say company has 100,000 authorized stocks; 40,000 outstanding stocks. Based on my understanding, after vesting period, those stocks become equivalent to that of a common stock that you may buy directly from the market (apps like Robinhood)
So, where do new employees keep getting new stocks from if there is a finite number of stocks available?