Mandel increased his Amazon stake by a sizable amount.Billionaire Steve Mandel and his hedge fund Lone Pine Capital have been a great one to follow for individual investors. Although some hedge funds have a poor record of underperforming the broader market, Mandel has substantially outperformed the market over the past three years. So, when he makes a move in his portfolio, investors should pay attention.One thing Mandel did during Q2 was sell off some of his Microsoft shares. Although it wasn't a massive m ...