Self-storage company Public Storage is buying National Storage Affiliates in an all-stock deal worth about $10.5 billion. National Storage has more than 1,000 properties, 69 million rentable square feet, and 550,000 units across 37 states and Puerto Rico. Public Storage said Monday that the acquisition will help expands its exposure to markets that are poised for strong long-term growth based on demographic trends, including the Sun Belt region.