The REIT's third-largest tenant faces tough macro and competitive headwinds.Realty Income (O 0.48%) is a popular dividend stock for income investors. It's one of the largest real estate investment trusts (REITs), with 15,540 properties worldwide and more than 1,500 different clients across 90 industries. Since its initial public offering (IPO) in 1994, it's kept its occupancy rate above 96%. It's also more balanced than many retail REITs because it primarily serves recession-resistant businesses, like disco ...