The mortgage REIT is seeing tailwinds in its business. Investors are undoubtedly attracted to mortgage real estate investment trusts, or mREITs, such as Annaly Capital Management (NLY -1.07%), for their high dividend yields. Annaly, for its part, currently sports about a 13.2% yield. Although investors might like these high yields, mREITs can sometimes be difficult to understand. With Annaly recently reporting its third-quarter results, let's look at the key metrics investors should pay attention to when co ...