Is it normal for companies to change their compensation package after starting?

I started in 2020 and my offer letter had my salary and an amt of stock for me to vest..This is a public company..A few months after I signed , they significantly reduced the amount of stock to grant me by about 50 %..Company cited that it would not be fair for other employees because stock price had fluctuated too much in my favor..Legally I cant do anything bc my offer letter said RSU grant was at the discretion of the board..I was told to wait and someone would fix this but I have given up hope now..I have never worked at a large company before..Is this normal behavior at large companys ?

This is not true, it really is at board discretion. Generally speaking many companies hesitate to even put stock offers in writing because of stuff like this. Whether they can do it legally (they can) and whether it's okay (it's not) are different here.

Yes, this is fairly normal.

I work for a big company that has a reputation for doing the right thing, which might have been true in the past but doesn't seem to apply now. I have seen them change grade structures, change promotion amounts, and change the pay/bonus structure all to the employees detriment. They always try to put some positive spin on it. I remember I brought up the topic of a raise with one boss because I was low in the pay scale for that grade. His response was that this was a good thing because it gave me room to grow. Seriously? I'd rather be near the top of the scale and not grow very much. Same thing for when we used to be able to count on 3 10% promotions but then they changed it to 4 7% promotions to get to similar compensation (it's actually below because the bonus isn't as good, not to mention it takes years longer to hit that 4th level).

Contrary to other replies, this is not remotely normal. Make sure you aren't misunderstanding the terms of your offer: some companies will say $x dollars worth of stock, with stock price determined by e.g. a 90-day running average. If there's a clause like that, and the stock went up so much since you joined (or signed the offer letter, depending on the terms) that the average price over the last 90 (or whatever) days is 2x higher than it was initially, then there's nothing shady going on.

If they didn't specify how they're determining a stock price to derive a # of shares from, or if they actually specified a number of shares rather than a dollar amount, then no, that's not normal. Get out and go somewhere else that doesn't play stupid games.

The terms were very clear..30 day avg for $x worth of stock so it was very easy to calculate what it shuld have been..

they changed the avg in their favor afterwards bc we joined on covid dip..