Brendan T. Cavanagh
Executive Vice President and Chief Financial Officer at SBA Communications
Thanks, Mark. Good evening. SBA had a tremendous quarter with results for the second quarter ahead of our expectations in most key areas. Total GAAP site leasing revenues for the second quarter were $524.1 million and cash site leasing revenues were $514.6 million. Foreign exchange rates were ahead of our previously forecasted FX rate estimates for the quarter, contributing $3.1 million of incremental site leasing revenue in the second quarter. They were also a tailwind on comparisons to the second quarter of 2020, positively impacting revenues by $3.5 million on a year-over-year basis.
Same tower recurring cash leasing revenue growth for the second quarter, which is calculated on a constant currency basis, was 3.4% over the second quarter of 2020, including the impact of 2.5% of churn. On a gross basis, same tower growth was 5.9%.
Domestic same tower recurring cash leasing revenue growth over the second quarter of last year was 5.5% on a gross basis and 3% on a net basis, including 2.5% of churn. Domestic operational leasing activity or bookings, representing new revenue placed under contract during the second quarter, was up significantly from the prior quarter and represented the highest quarterly level since 2014. Even with this high level of executions, our domestic new lease and new amendment application backlog finished the quarter at a multi-year high. These backlog support our expectations for continued strong domestic operational leasing activity throughout the balance of this year.
During the second quarter, amendment activity represented 34% of our domestic bookings with 66% coming from new leases, the first time in many years the bookings from new leases outpaced that from amendment. The Big 4 carriers of AT&T, T-Mobile, Verizon and DISH represented 97% of total incremental domestic leasing revenue signed up during the quarter. Internationally, on a constant currency basis, same tower cash leasing revenue growth was 5.3% net, including 2.2% of churn or 7.5% on a gross basis.
International leasing activity increased modestly from the first quarter. In Brazil, our largest international market, we had an improved quarter of leasing activity. Gross same tower organic growth in Brazil was 8.9% on a constant currency basis. During the second quarter, 84.8% of consolidated cash site leasing revenue was denominated in US dollars.
The majority of non-US dollar denominated revenue was from Brazil with Brazil representing 11.5% of consolidated cash site leasing revenues during the quarter and 8.4% of cash site leasing revenue excluding revenues from pass through expenses. So, our cash flow for the second quarter was $421.2 million.
Our tower cash flow margins continue to be very strong with the second quarter Domestic tower cash flow margin of 84.7% and an international tower cash flow margin of 70.8% or 91%, excluding the impact of pass-through reimbursable expenses.
Adjusted EBITDA in the second quarter was $400.2 million. The adjusted EBITDA margin was 70.7% in the quarter. Excluding the impact of revenues from pass-through expenses, adjusted EBITDA margin was 75%. Approximately 98% of our total adjusted EBITDA was attributable to our tower leasing business in the second quarter. During the second quarter, our services business produced record results for the company with $51.4 million in revenue and over $11 million of segment operating profit.
The very high activity levels we saw in the first quarter strengthened further in the second quarter, resulting in a quarter end services backlog that was 30% above first quarter levels and was also the highest in our company's history. We expect to see continued high levels of services activity throughout the rest of the year and as a result have increased our full-year outlook for site development revenue by $25 million from last quarter and by $40 million from our initial outlook.
AFFO in the second quarter was $293.5 million. AFFO per share was $2.64, an increase of 15.3% over the second quarter of 2020. During the second quarter, we continued to expand our portfolio acquiring 57 communication sites for a total cash consideration of $67 million. We also built 98 new sites in the quarter. Subsequent to quarter end, we have purchased or agreed to purchase approximately 400 additional sites in our existing markets for an aggregate price of $95 million. And we anticipate closing on the majority of the sites under contract by the end of the year.
In addition, during the second quarter, we announced that through a new joint venture arrangement, we have entered into a contract with Airtel Tanzania, a subsidiary of Airtel Africa, to purchase their approximately 1,400 towers in Tanzania. Under this agreement, Airtel will leaseback space on each of the towers and we'll also provide a fixed minimum number of build-to-suit towers during the first five years following the closing of the acquisition. The total purchase price for the acquisition is expected to be approximately $175 million and the acquisition is anticipated to close in stages starting in the fourth quarter.
For our updated 2021 outlook, we have assumed that the acquisition closes at the end of the year. And thus, we have included the entire purchase price in our outlook for discretionary capital expenditures. But we have included no revenue or tower cash flow associated with these events. We expect the assets to produce approximately $80 million of adjusted EBITDA during the first full year of operations under the joint venture. SBA will be the majority partner for joint venture and we are partnering with Paradigm Infrastructure Limited, a UK company founded by former senior executives of American Tower, which is focused on developing, owning and operating shared passive wireless infrastructure in selected growth markets.
We believe the combined international tower industry operating experience of SBA and Paradigm will allow us to maximize the opportunity in this new rapidly growing market. In addition to do tower assets, we also continue to invest in the land under our sites. During the quarter, we spent an aggregate of $11.8 million to buy land and easements and to extend ground lease terms.
At the end of the quarter, we owned or controlled for more than 20 years the land underneath approximately 71% of our towers. And the average remaining life under our ground leases, including renewal options under our control, is approximately 37 years.
In this afternoon's earnings press release, we included our updated outlook for full year '21. Our update increased expectations for site leasing revenue, site development revenue, adjusted EBITDA, AFFO and AFFO per share. These increases are driven by outperformance across our business, increased network investment activities by our customers, improved foreign exchange rates, reduced non-discretionary cash capital expenditures and reduced cash interest expense as a result of timely refinancings.
Notwithstanding our strong domestic leasing bookings during the second quarter, which were ahead of our expectations, we have not increased our 2021 outlook for incremental organic domestic leasing revenue. New bookings typically begin to accrue revenue at the earlier of a date-certain or commencement of construction. For outlook purposes, unless we have received notice of construction commencement, we only consider the date certain, which for the second quarter bookings to outperformance generally ranges from late in the fourth quarter sometime in the first half of 2022.
As we mentioned last quarter, we anticipate our reported gross domestic same tower revenue growth will begin to increase in the second half of the year and that we will exit 2021 at the highest rate of the year. As is always the case, our full year 2021 outlook does not assume any further acquisitions beyond those under contract today. And the outlook also does not assume any share repurchases other than those completed as of today. However, when opportunities present, we are likely to invest in additional assets or share repurchases or both during the rest of the year.
Our outlook for net cash interest expense did not contemplate any further financing activity in 2021. Finally, our outlook for AFFO per share is based on an assumed weighted average number of diluted common shares of 111.5 million, which assumption is influenced in part by estimated future share prices.
With that, I will now turn things over to Mark, who will provide an update on our liquidity position and balance sheet.