If you are talking about the intrinsic value of your company's stock increasing, then it's definitely not a zero sum game. But they do pay out part of their pro

If you are talking about the intrinsic value of your company's stock increasing, then it's definitely not a zero sum game. But they do pay out part of their profits (intrinsic value gains) as dividend. If we consider just the stock price fluctuations due to demand/supply (and no changes in the intrinsic value), then it is a zero sum game.