New to the game.

Is there any way to stop a hostile takeover?  It won't let me buy my own stock back if someone else owns it.  But it will let me buy stock in other companies even if someone else owns it?  I'm in a game now and I'm about to lose because I can't stop the takeover.  I have tons of cash, but not enough to completely buy out the person who is about to buy me out.  I have plenty of cash to buy my own stock from them (at double value), but the buy button is unclickable.

Am I missing something, or is this just the way it is?