AGNC Investment (AGNC -0.10%) has a massive 14.4% dividend yield. To put that into context, the average real estate investment trust (REIT) yields just 3.9%, using Vanguard Real Estate Index ETF (VNQ -0.67%) as a proxy. It's easy to see why a yield-hungry investor might want to learn more about AGNC. Fortunately, for most folks, the buy, sell, or hold call here will end up being pretty simple. But there's still a small group of investors that don't fit the common mold.The problem with AGNC InvestmentTo get ...