Welltower is a big dividend (4.4%) healthcare REIT. It's an income-investor favorite not only because of its big dividend, but also because of the perceived long-term demographic tailwinds at its back (the aging population). In this article, we review some of the more significant risk factors that could potentially derail Welltower's outstanding long-term track record including healthcare reform, the company’s already large size, valuation, dividend sustainability, lawsuits and REIT laws.