My two cents... He might think the bubble is about to burst; he might be hedging his downside risk after a serious rise in his overall portfolio, picking the two stocks he thinks are the most out of whack valuation-wise to execute that hedge (the premium for the puts would likely be a fraction of the paper gain he's sitting on so not the end of the world if they expire worthless); he might be hedging significant material gains in these exact two stocks; he might be doing it for some only-billionaires-get-it reason. I guess I'm just saying that the reason could be pretty detached from "I think the bubble is about to burst!"