SBA Communications owns and operates over 30,000 cell towers throughout North America and South America. It leases space on its towers to wireless service providers, who install equipment on the towers to support their wireless networks. The company has a very concentrated customer base, with most revenue in each market being generated by just the top few mobile carriers. The company owns more than 16,000 towers in the U.S., which accounted for three fourths of the company's total revenue in 2019. Internationally, SBA's greatest presence is in Brazil, where it operates roughly 10,000 towers. SBA operates as a real estate investment trust, or REIT.