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(a)	See reconciliation of this non-GAAP financial measure to net income (loss) included herein.

(b)	As issued on January 25, 2017.

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•

Site rental revenues. Site rental revenues grew approximately 7%, or $58 million, from first quarter 2016 to first quarter 2017, inclusive of approximately $34 million in Organic Contribution to Site Rental Revenues plus $40 million in contributions from acquisitions and other items, less a $16 million reduction in straight-line revenues. The $34 million in Organic Contribution to Site Rental Revenues represents approximately 4% growth, comprised of approximately 8% growth from new leasing activity and contracted tenant escalations, net of approximately 4% from tenant non-renewals.

•

Capital expenditures and acquisitions. Capital expenditures during the quarter were approximately $262 million, comprised of approximately $21 million of land purchases, approximately $16 million of sustaining capital expenditures and approximately $225 million of revenue generating capital expenditures. During the quarter, Crown Castle also closed on its previously announced acquisition of FiberNet for approximately $1.5 billion.

•	Common stock dividend. During the quarter, Crown Castle paid common stock dividends of approximately $348 million in the aggregate, or $0.95 per common share, an increase of approximately 7% on a per share basis compared to the same period a year ago.

•

Financing activities. In January, Crown Castle issued $500 million in aggregate principal amount of senior unsecured notes and increased the size of its existing term loan facility by $500 million. Proceeds from both transactions were used to refinance existing debt. Further, Crown Castle extended the maturity of its existing revolving credit and term loan facilities from January 2021 to January 2022.

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(a)	See reconciliation of this non-GAAP financial measure to net income (loss) included herein.

(b)	See the reconciliation of "components of interest expense and amortization of deferred financing costs" herein for a discussion of non-cash interest expense.

(c)	The assumption for second quarter 2017 and full year 2017 diluted weighted-average common shares outstanding is based on diluted common shares outstanding as of March 31, 2017.

(a)	See reconciliation of this non-GAAP financial measure to net income (loss) included herein.

(b)	As issued on January 25, 2017. Represents midpoint of Outlook.

(c)	The assumption for full year 2017 diluted weighted-average common shares outstanding is based on diluted common shares outstanding as of March 31, 2017.

•

The increase in full year 2017 Outlook primarily reflects the outperformance in the first quarter and an increase in expected gross margin contribution from network services for the remainder of the year. This increase is partially offset by higher anticipated site rental costs of approximately $10 million for additional employees and sustaining capital expenditures of approximately $5 million related to additional office space necessary to increase our small cell production to deliver on contracts to build 25,000 new small cell nodes in 2018 and beyond.

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•	The chart below reconciles the components of expected growth from 2016 to 2017 in site rental revenues of $240 million to $270 million, including expected Organic Contribution to Site Rental Revenues of approximately $140 million to $170 million.

•	The chart below reconciles the components of expected growth in AFFO from 2016 to 2017 of approximately $210 million at the midpoint.

•	Network services gross margin contribution for full year 2017 is expected to be approximately $255 million to $270 million.

•	The current full year 2017 Outlook does not include contribution from the recently announced acquisition of Wilcon Holdings LLC ("Wilcon"), which is expected to close in the third quarter of 2017. In the first full year of Crown Castle’s ownership, Wilcon is expected to contribute approximately $40 million to gross margin and approximately

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•	Compared to first quarter 2017, the midpoint of second quarter 2017 Outlook for site rental gross margin, Adjusted EBITDA and AFFO are expected to be impacted by certain seasonal or timing items, including approximately $6 million, $8 million and $9 million of higher repair and maintenance expense, sustaining capital expenditures and cash tax payments, respectively.

•	Additional information is available in Crown Castle's quarterly Supplemental Information Package posted in the Investors section of its website.

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•

Adjusted EBITDA is useful to investors or other interested parties in evaluating our financial performance. Adjusted EBITDA is the primary measure used by management (1) to evaluate the economic productivity of our operations and (2) for purposes of making decisions about allocating resources to, and assessing the performance of, our operations. Management believes that Adjusted EBITDA helps investors or other interested parties meaningfully evaluate and compare the results of our operations (1) from period to period and (2) to our competitors, by removing the impact of our capital structure (primarily interest charges from our outstanding debt) and asset base (primarily depreciation, amortization and accretion) from our financial results. Management also believes Adjusted EBITDA is frequently used by investors or other interested parties in the evaluation of the wireless infrastructure sector and other REITs to measure financial performance without regard to items such as depreciation, amortization and accretion which can vary depending upon accounting methods and the book value of assets. In addition, Adjusted EBITDA is similar to the measure of current financial performance generally used in our debt covenant calculations. Adjusted EBITDA should be considered only as a supplement to net income computed in accordance with GAAP as a measure of our performance.

•

AFFO is useful to investors or other interested parties in evaluating our financial performance. Management believes that AFFO helps investors or other interested parties meaningfully evaluate our financial performance as they include (1) the impact of our capital structure (primarily interest expense on our outstanding debt and dividends on our preferred stock) and (2) sustaining capital expenditures, and exclude the impact of our (1) asset base (primarily depreciation, amortization and accretion) and (2) certain non-cash items, including straight-lined revenues and expenses related to fixed escalations and rent free periods. GAAP requires rental revenues and expenses related to leases that contain specified rental increases over the life of the lease to be recognized evenly over the life of the lease. In accordance with GAAP, if payment terms call for fixed escalations, or rent free periods, the revenue or expense is recognized on a straight-lined basis over the fixed, non-cancelable term of the contract. Management notes that the Company uses AFFO only as a performance measure. AFFO should be considered only as a supplement to net income computed in accordance with GAAP as a measure of our performance and should not be considered as an alternative to cash flows from operations or as residual cash flow available for discretionary investment.

•

FFO is useful to investors or other interested parties in evaluating our financial performance. Management believes that FFO may be used by investors or other interested parties as a basis to compare our financial performance with that of other REITs. FFO helps investors or other interested parties meaningfully evaluate financial performance by excluding the impact of our asset base (primarily depreciation, amortization and accretion). FFO is not a key performance indicator used by the Company. FFO should be considered only as a supplement to net income computed in accordance with GAAP as a measure of our performance and should not be considered as an alternative to cash flow from operations.

•

Organic Contribution to Site Rental Revenues is useful to investors or other interested parties in understanding the components of the year-over year changes in our site rental revenues computed in accordance with GAAP. Management uses the Organic Contribution to Site Rental Revenues to assess year-over-year growth rates for our rental activities, to evaluate current performance, to capture trends in rental rates, new leasing activities and customer non-renewals in our core business, as well to forecast future results. Organic Contribution to Site Rental Revenues is not meant as an alternative measure of revenue and should be considered only as a supplement in understanding and assessing the performance of our site rental revenues computed in accordance with GAAP.

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(a)	See the reconciliation of "components of interest expense and amortization of deferred financing costs" herein for a discussion of non-cash interest expense.

(b)	See "Non-GAAP Financial Measures and Other Calculations" herein for a discussion of our definition of Adjusted EBITDA.

(c)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

(a)	See the reconciliation of "components of interest expense and amortization of deferred financing costs" herein for a discussion of non-cash interest expense.

(b)	See "Non-GAAP Financial Measures and Other Calculations" herein for a discussion of our definition of Adjusted EBITDA.

(c)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(a)	See "Non-GAAP Financial Measures and Other Calculations" herein for a discussion of our definitions of FFO and AFFO.

(b)	FFO and AFFO are reduced by cash paid for preferred stock dividends.

(c)	Diluted weighted-average common shares outstanding were 361.7 million, 334.9 million and 340.9 million for the three months ended March 31, 2017 and 2016, and the twelve months ended December 31, 2016, respectively.

(d)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(a)	The assumption for second quarter 2017 and full year 2017 diluted weighted-average common shares outstanding is 362 million based on diluted common shares outstanding as of March 31, 2017.

(b)	See "Non-GAAP Financial Measures and Other Calculations" herein for a discussion for our definitions of FFO and AFFO.

(c)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(a)	See "Non-GAAP Financial Measures and Other Calculations" herein for a discussion of our definition of Adjusted EBITDA.

(b)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

(a)	Previously issued first quarter 2017 and full year 2017 outlook assumes diluted common shares outstanding as of December 31, 2016 of approximately 361 million shares.

(b)	See "Non-GAAP Financial Measures and Other Calculations" herein for a discussion for our definitions of FFO and AFFO.

(c)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(a)	Includes revenues from amortization of prepaid rent in accordance with GAAP.

(b)	The financial impact of acquisitions, as measured by the initial contribution, and tower builds is excluded from Organic Contribution to Site Rental Revenues until the one-year anniversary of the acquisition or build.

(c)	Includes revenues from the construction of new small cell nodes, exclusive of straight-lined revenues related to fixed escalators.

(d)	See "Non-GAAP Financial Measures and Other Calculations" herein.

(e)	Calculated as the percentage change from prior year site rental revenues exclusive of straight-lined revenues associated with fixed escalations compared to Organic Contribution to Site Rental Revenues for the current period.

(f)	Additional information regarding Crown Castle's site rental revenues including projected revenue from customer licenses, tenant non-renewals, straight-lined revenues and prepaid rent is available in Crown Castle's quarterly Supplemental Information Package posted in the Investors section of its website.

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(a)	Includes revenues from amortization of prepaid rent in accordance with GAAP.

(b)	The financial impact of acquisitions, as measured by the initial contribution, and tower builds is excluded from Organic Contribution to Site Rental Revenues until the one-year anniversary of the acquisition or build.

(c)	Includes revenues from the construction of new small cell nodes, exclusive of straight-lined revenues related to fixed escalators.

(d)	See "Non-GAAP Financial Measures and Other Calculations" herein.

(e)	Calculated as the percentage change from prior year site rental revenues exclusive of straight-lined revenues associated with fixed escalations compared to Organic Contribution to Site Rental Revenues for the current period.

(f)	Calculated based on midpoint of Full Year 2017 Outlook.

(g)	Additional information regarding Crown Castle's site rental revenues including projected revenue from customer licenses, tenant non-renewals, straight-lined revenues and prepaid rent is available in Crown Castle's quarterly Supplemental Information Package posted in the Investors section of its website.

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(a)	The Senior Secured Notes, Series 2009-1, Class A-1 principal amortizes during the period beginning January 2010 and ending in 2019 and the Senior Secured Notes, 2009-1, Class A-2 principal amortizes during the period beginning in 2019 and ending in 2029.

(b)	The Senior Secured Tower Revenue Notes, Series 2010-3 and 2010-6 have anticipated repayment dates in 2020. The Senior Secured Tower Revenue Notes, Series 2015-1 and 2015-2 have anticipated repayment dates in 2022 and 2025, respectively.

(c)	Excludes restricted cash.

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(a)	Excludes restricted cash.

(b)	The Net Debt to Last Quarter Annualized Adjusted EBITDA calculation does not give effect to a full quarter of ownership of FiberNet, as this acquisition closed on January 17, 2017.

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•

Our business depends on the demand for our wireless infrastructure, driven primarily by demand for wireless connectivity, and we may be adversely affected by any slowdown in such demand. Additionally, a reduction in the amount or change in the mix of carrier network investment may materially and adversely affect our business (including reducing demand for new tenant additions and network services).

•	A substantial portion of our revenues is derived from a small number of customers, and the loss, consolidation or financial instability of any of our limited number of customers may materially decrease revenues or reduce demand for our wireless infrastructure and network services.

•	The business model for small cells contains differences from our traditional site rental business, resulting in different operational risks. If we do not successfully operate that business model or identify or manage those operational risks, such operations may produce results that are less than anticipated.

•	Our substantial level of indebtedness could adversely affect our ability to react to changes in our business, and the terms of our debt instruments limit our ability to take a number of actions that our management might otherwise believe to be in our best interests. In addition, if we fail to comply with our covenants, our debt could be accelerated.

•	We have a substantial amount of indebtedness. In the event we do not repay or refinance such indebtedness, we could face substantial liquidity issues and might be required to issue equity securities or securities convertible into equity securities, or sell some of our assets to meet our debt payment obligations.

•	Sales or issuances of a substantial number of shares of our common stock may adversely affect the market price of our common stock.

•	As a result of competition in our industry, we may find it more difficult to achieve favorable rental rates on our new or renewing tenant leases.

•	New technologies may reduce demand for our wireless infrastructure or negatively impact our revenues.

•	The expansion and development of our business, including through acquisitions, increased product offerings or other strategic growth opportunities, may cause disruptions in our business, which may have an adverse effect on our business, operations or financial results.

•	If we fail to retain rights to our wireless infrastructure, including the land interests under our towers, our business may be adversely affected.

•	Our network services business has historically experienced significant volatility in demand, which reduces the predictability of our results.

•	New wireless technologies may not deploy or be adopted by customers as rapidly or in the manner projected.

•	If we fail to comply with laws and regulations which regulate our business and which may change at any time, we may be fined or even lose our right to conduct some of our business.

•	If radio frequency emissions from wireless handsets or equipment on our wireless infrastructure are demonstrated to cause negative health effects, potential future claims could adversely affect our operations, costs or revenues.

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•	Certain provisions of our restated certificate of incorporation, amended and restated by-laws and operative agreements, and domestic and international competition laws may make it more difficult for a third party to acquire control of us or for us to acquire control of a third party, even if such a change in control would be beneficial to our stockholders.

•	We may be vulnerable to security breaches that could adversely affect our business, operations, and reputation.

•

Future dividend payments to our stockholders will reduce the availability of our cash on hand available to fund future discretionary investments, and may result in a need to incur indebtedness or issue equity securities to fund growth opportunities. In such event, the then current economic, credit market or equity market conditions will impact the availability or cost of such financing, which may hinder our ability to grow our per share results of operations.

•	Remaining qualified to be taxed as a REIT involves highly technical and complex provisions of the US Internal Revenue Code. Failure to remain qualified as a REIT would result in our inability to deduct dividends to stockholders when computing our taxable income, which would reduce our available cash.

•	Complying with REIT requirements, including the 90% distribution requirement, may limit our flexibility or cause us to forgo otherwise attractive opportunities, including certain discretionary investments and potential financing alternatives.

•	REIT related ownership limitations and transfer restrictions may prevent or restrict certain transfers of our capital stock.

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(a)

Segment cost of operations exclude (1) stock-based compensation expense of $4.9 million and $8.3 million for the three months ended March 31, 2017 and 2016, respectively and (2) prepaid lease purchase price adjustments of $5.1 million and $5.2 million for the three months ended March 31, 2017 and 2016, respectively. Segment general and administrative expenses exclude stock-based compensation expense of $20.1 million and $22.4 million for the three months ended March 31, 2017 and 2016, respectively.

(c)	See condensed consolidated statement of operations for further information.

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•

Grow cash flows from our wireless infrastructure. We seek to maximize our site rental cash flows by working with our customers to provide them quick access to our wireless infrastructure and entering into associated long-term leases. Tenant additions or modifications of existing tenant equipment (collectively, "tenant additions") enable our customers to expand coverage and capacity in order to meet increasing demand for wireless connectivity, while generating high incremental returns for our business. We believe our product offerings of Towers and Small Cells provide a comprehensive solution to our customers' growing connectivity needs through our shared wireless infrastructure model, which is an efficient and cost effective way to serve our customers. We also believe that there will be considerable future demand for our wireless infrastructure based on the location of our wireless infrastructure and the rapid growth in wireless connectivity, which will lead to future growth in the wireless industry.

•

Return cash provided by operating activities to stockholders in the form of dividends. We believe that distributing a meaningful portion of our cash provided by operating activities appropriately provides stockholders with increased certainty for a portion of expected long-term stockholder value while still retaining sufficient flexibility to invest in our business and deliver growth. We believe this decision reflects the translation of the high-quality, long-term contractual cash flows of our business into stable capital returns to stockholders.

•	Invest capital efficiently to grow cash flows and long-term dividends per share. We seek to invest our available capital, including the net cash provided by our operating activities and external financing sources, in a manner that will increase long-term stockholder value on a risk-adjusted basis. Our historical investments have included the following (in no particular order):

◦	purchases of shares of our common stock from time to time;

◦	acquisitions or construction of wireless infrastructure;

◦	acquisitions of land interests under towers;

◦	improvements and structural enhancements to our existing wireless infrastructure; or

◦	purchases, repayment or redemption of our debt.

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(1)	See reconciliations and definitions provided herein. See also "Definitions of Non-GAAP Financial Measures and Other Calculations" in the Appendix for a discussion of our definitions of FFO and AFFO.

(2)	AFFO per share represents the midpoint of the full year 2017 outlook as issued on April 24, 2017.

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(1)	Nominating & Corporate Governance Committee

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(1)	Based on the sales price, adjusted for common stock dividends, as reported by Bloomberg.

(2)	Based on the period end closing price, adjusted for common stock dividends, as reported by Bloomberg.

(3)	Period end market value of outstanding common shares is calculated as the product of (a) shares of common stock outstanding at period end and (b) closing share price at period end, adjusted for common stock dividends, as reported by Bloomberg.

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(1)	Excludes small cells and third-party land interests.

(2)	Excludes renewal terms at customers' option.

(3)	Excludes renewal terms at customers' option, weighted by site rental revenues.

(4)	Includes renewal terms at the Company's option, weighted by site rental gross margin.

(5)	See reconciliations of Non-GAAP financial measures provided herein. See also "Definitions of Non-GAAP Measures and Other Calculations" in the Appendix for a discussion of our definitions of FFO and AFFO.

(6)	Based on diluted weighted-average common shares outstanding of 361.7 million and 334.9 million for the three months ended March 31, 2017 and 2016, respectively.

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(1)	Includes net cash used for acquisitions of approximately $1.5 billion and $22 million for the three months ended March 31, 2017 and 2016, respectively.

(2)	Balances reflect debt issuance costs as a direct reduction from the respective carrying amounts of debt, with the exception of debt issuance costs associated with the Company's revolving credit facilities.

(3)	The Net Debt to Last Quarter Annualized Adjusted EBITDA calculation does not give effect to a full quarter of ownership of FiberNet, as this acquisition closed on January 17, 2017.

(4)	The assumption for second quarter 2017 and full year 2017 diluted weighted-average common shares outstanding is 362 million based on diluted common shares outstanding as of March 31, 2017.

(5)	See reconciliation of this non-GAAP financial measure to net income (loss) included herein.

(6)	See the reconciliation of "components of interest expense and amortization of deferred financing costs" in the Appendix.

(7)	Calculated using net income (loss) attributable to CCIC common stockholders.

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(1)	Includes revenues from amortization of prepaid rent in accordance with GAAP.

(2)	The financial impact of acquisitions, as measured by the initial contribution, and tower builds is excluded from Organic Contribution to Site Rental Revenues until the one-year anniversary of the acquisition or build.

(3)	Includes revenues from the construction of new small cell nodes, exclusive of straight-lined revenues related to fixed escalators.

(4)	See definitions provided herein.

(5)	Calculated as the percentage change from prior year site rental revenues exclusive of straight-lined revenues associated with fixed escalations compared to Organic Contribution to Site Rental Revenues for the current period.

(6)	Calculated based on midpoint of Full Year 2017 Outlook.

(7)	See additional information regarding Crown Castle's site rental revenues including projected revenue from customer licenses, tenant non-renewals, straight-lined revenues and prepaid rent herein.

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(1)

Segment cost of operations exclude (1) stock-based compensation expense of $4.9 million and $8.3 million for the three months ended March 31, 2017 and 2016, respectively and (2) prepaid lease purchase price adjustments of $5.1 million and $5.2 million for the three months ended March 31, 2017 and 2016, respectively. Segment general and administrative expenses exclude stock-based compensation expense of $20.1 million and $22.4 million for the three months ended March 31, 2017 and 2016, respectively.

(2)	See "Definitions of Non-GAAP Financial Measures and Other Calculations" in the Appendix for a discussion of our definitions of our definitions of segment site rental gross margin, segment network service and other gross margin and segment operating profit.

(3)	See condensed consolidated statement of operations for further information.

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(1)	See "Definitions of Non-GAAP Measures and Other Calculations" in the Appendix for a discussion of our definitions of FFO and AFFO.

(2)	FFO and AFFO are reduced by cash paid for preferred stock dividends.

(3)	Based on the diluted weighted-average common shares outstanding for the three months ended March 31, 2017 and 2016.

(4)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(1)	Includes revenues from amortization of prepaid rent in accordance with GAAP.

(2)	The financial impact of acquisitions, as measured by the initial contribution, and tower builds is excluded from Organic Contribution to Site Rental Revenues until the one-year anniversary of the acquisition or build.

(3)	Includes revenues from the construction of new small cell nodes, exclusive of straight-lined revenues related to fixed escalators.

(4)	See definitions provided herein.

(5)	Calculated as the percentage change from prior year site rental revenues exclusive of straight-lined revenues associated with fixed escalations compared to Organic Contribution to Site Rental Revenues for the current period.

(6)	See additional information regarding Crown Castle's site rental revenues including projected revenue from customer licenses, tenant non-renewals, straight-lined revenues and prepaid rent herein.

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(1)	In accordance with GAAP accounting, if payment terms call for fixed escalations, or rent free periods, the revenue is recognized on a straight-line basis over the fixed, non-cancelable term of the contract. Since the Company recognizes revenue on a straight-line basis, a portion of the site rental revenue in a given period represents cash collected or contractually collectible in other periods.

(2)	Reflects up front payments received from long-term tenant contracts and other deferred credits (commonly referred to as prepaid rent), and the amortization thereof for GAAP revenue recognition purposes.

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(1)	Based on customer licenses as of March 31, 2017. All customer licenses are assumed to renew for a new term at current term end date. CPI-linked customer contracts are assumed to escalate at 3% per annum.

(2)	Based on existing ground leases as of March 31, 2017. CPI-linked leases are assumed to escalate at 3% per annum.

(3)	Reflects lease renewals by year by customer; dollar amounts represent annualized cash site rental revenues from assumed renewals or extension as reflected in the table "Projected Revenue from Customer Contracts."

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(1)	Estimated impact to site rental revenues in the applicable period based on the anticipated timing and amount of decommissioning activity, as of March 31, 2017.

(2)	Depending on the eventual network deployment and decommissioning plans of AT&T, T-Mobile and Sprint, the impact and timing of such renewals may vary from Crown Castle's expectations.

(3)	Weighted by site rental revenue contributions; excludes renewals at the customers' option.

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(1)	Yield is calculated as LQA site rental gross margin divided by invested capital.

(2)	Reflects gross total assets, including incremental capital invested by the Company since time of acquisition or construction completion. Inclusive of invested capital related to land at the tower site.

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(1)	Includes towers and rooftops, excludes small cells and third-party land interests.

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(1)	Includes towers and rooftops, excludes small cells and third-party land interests.

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(1)	Includes towers and rooftops, excludes small cells and third-party land interests.

(2)	Includes renewal terms at the Company’s option; weighted by site rental gross margin.

(1)	Includes the impact from the amortization of lump sum payments.

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(1)	Represents the weighted-average stated interest rate.

(2)	Represents the applicable amount of debt divided by LQA consolidated Adjusted EBITDA. The Net Debt to Last Quarter Annualized Adjusted EBITDA calculation does not give effect to a full quarter of ownership of FiberNet, as this acquisition closed on January 17, 2017.

(3)

If the respective series of such debt is not paid in full on or prior to an applicable date then the Excess Cash Flow (as defined in the indenture) of the issuers of such notes will be used to repay principal of the applicable series, and additional interest (of an additional approximately 5% per annum) will accrue on the respective series. The Senior Secured Tower Revenue Notes, Series 2010-3 and 2010-6 have anticipated repayment dates in 2020. The Senior Secured Tower Revenue Notes, Series 2015-1 and 2015-2 have anticipated repayment dates of 2022 and 2025, respectively. Notes are prepayable at par if voluntarily repaid six months or less prior to maturity; earlier prepayment may require additional consideration.

(4)	As of March 31, 2017, the undrawn availability under the $2.5 billion Revolving Credit Facility is $2.2 billion.

(5)	Market capitalization calculated based on $94.45 closing price and 360.5 million shares outstanding as of March 31, 2017.

(6)	Represents the sum of net debt and market capitalization.

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(1)	Where applicable, maturities reflect the Anticipated Repayment Date as defined in the respective debt agreement; excludes capital leases and other obligations; amounts presented at face value net of repurchases held at CCIC.

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(1)	We have an At-The-Market stock offering program ("ATM Program") through which we may, from time to time, issue and sell shares of our common stock having an aggregate cumulative gross sales price of up to $500.0 million to or through sales agents. As of March 31, 2017, 4.1 million shares of common stock had been sold under the ATM Program generating net proceeds of $346.3 million.

(2)	Exclusive of restricted cash.

(3)	Availability at any point in time is subject to reaffirmation of the representations and warranties in, and there being no default under, our credit agreement governing our Senior Unsecured Credit Facility.

(4)	Balances reflect debt issuance costs as a direct reduction from the respective carrying amounts of debt, with the exception of debt issuance costs associated with the Company's revolving credit facilities.

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(1)	As defined in the respective debt agreement. In the indentures for the 2010 Tower Revenue Notes. 2015 Tower Revenue Notes and the 2009 Securitized Notes, the defined term for Debt Service Coverage Ratio is "DSCR".

(2)	Failure to comply with the financial maintenance covenants would, absent a waiver, result in an event of default under the credit agreement governing our 2016 Credit Facility.

(3)	Applicable solely to the extent that the senior unsecured debt rating by any two of S&P, Moody's and Fitch is lower than BBB-, Baa3 or BBB-, respectively. If applicable, the consolidated interest coverage ratio must be greater than or equal to 2.50.

(4)

The 2010 Tower Revenue Notes, 2015 Tower Revenue Notes, and 2009 Securitized Notes also include the potential for amortization events, which could result in applying current and future cash flow to the prepayment of debt with applicable prepayment consideration. An amortization event occurs when the Debt Service Coverage Ratio falls below 1.45x, 1.45x or 1.15x, in each case as described under the indentures for the 2010 Tower Revenue Notes, 2015 Tower Revenue Notes, or 2009 Securitized Notes, respectively.

(5)	Rating Agency Confirmation (as defined in the respective debt agreement) is also required.

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(1)	Excludes capital lease and other obligations.

(2)	Face value net of required amortizations; assumes no maturity or balloon principal payments; excludes capital leases.

(3)	Interest expense calculated based on current interest rates.

(4)	Interest expense calculated based on current interest rates until the sooner of the (1) stated maturity date or (2) the Anticipated Repayment Date, at which time the face value amount outstanding of such indebtedness is refinanced at current rates plus 12.5 bps.

(5)	Interest expense calculated based on current interest rates. Forward LIBOR assumptions are derived from the 1-month LIBOR forward curve as of March 31, 2017. Calculation assumes no changes to future interest rate margin spread over LIBOR due to changes in the Borrower’s senior unsecured credit rating.

(6)	Interest expense calculated based on current interest rates using the 1-month LIBOR forward curve as of March 31, 2017 plus 12.5 bps.

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•

Adjusted EBITDA is useful to investors or other interested parties in evaluating our financial performance. Adjusted EBITDA is the primary measure used by management (1) to evaluate the economic productivity of our operations and (2) for purposes of making decisions about allocating resources to, and assessing the performance of, our operations. Management believes that Adjusted EBITDA helps investors or other interested parties meaningfully evaluate and compare the results of our operations (1) from period to period and (2) to our competitors, by removing the impact of our capital structure (primarily interest charges from our outstanding debt) and asset base (primarily depreciation, amortization and accretion) from our financial results. Management also believes Adjusted EBITDA is frequently used by investors or other interested parties in the evaluation of the wireless infrastructure sector and other REITs to measure financial performance without regard to items such as depreciation, amortization and accretion, which can vary depending upon accounting methods and the book value of assets. In addition, Adjusted EBITDA is similar to the measure of current financial performance generally used in our debt covenant calculations. Adjusted EBITDA should be considered only as a supplement to net income computed in accordance with GAAP as a measure of our performance.

•

AFFO and AFFO per share are useful to investors or other interested parties in evaluating our financial performance. Management believes that AFFO and AFFO per share help investors or other interested parties meaningfully evaluate our financial performance as they include (1) the impact of our capital structure (primarily interest expense on our outstanding debt and dividends on our preferred stock) and (2) sustaining capital expenditures and exclude the impact of our (1) asset base (primarily depreciation, amortization and accretion) and (2) certain non-cash items, including straight-lined revenues and expenses related to fixed escalations and rent free periods. GAAP requires rental revenues and expenses related to leases that contain specified rental increases over the life of the lease to be recognized evenly over the life of the lease. In accordance with GAAP, if payment terms call for fixed escalations, or rent free periods, the revenue or expense is recognized on a straight-lined basis over the fixed, non-cancelable term of the contract. Management notes that the Company uses AFFO and AFFO per share only as a performance measure. AFFO and AFFO per share should be considered only as a supplement to net income computed in accordance with GAAP as a measure of our performance and should not be considered as an alternative to cash flows from operations or as residual cash flow available for discretionary investment.

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FFO and FFO per share are useful to investors or other interested parties in evaluating our financial performance. Management believes that FFO may be used by investors or other interested parties as a basis to compare our financial performance with that of other REITs. FFO and FFO per share help investors or other interested parties meaningfully evaluate financial performance by excluding the impact of our asset base (primarily depreciation, amortization and accretion). FFO and FFO per share are not key performance indicators used by the Company. FFO and FFO per share should be considered only as a supplement to net income computed in accordance with GAAP as a measure of our performance and should not be considered as an alternative to cash flow from operations.

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Organic Contribution to Site Rental Revenues is useful to investors or other interested parties in understanding the components of the year-over year changes in our site rental revenues computed in accordance with GAAP. Management uses the Organic Contribution to Site Rental Revenues to assess year-over-year growth rates for our rental activities, to evaluate current performance, to capture trends in rental rates, new leasing activities and customer non-renewals in our core business, as well to forecast future results. Organic Contribution to Site Rental Revenues is not meant as an alternative measure of revenue and

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(1)	See the reconciliation of "components of interest expense and amortization of deferred financing costs" herein.

(2)	See "Definitions of Non-GAAP Measures and Other Calculations" herein for a discussion of our definition of Adjusted EBITDA.

(3)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(1)	See the reconciliation of "components of interest expense and amortization of deferred financing costs" herein.

(2)	See "Definitions of Non-GAAP Measures and Other Calculations" herein for a discussion of our definition of Adjusted EBITDA.

(3)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(1)	See “Definitions of Non-GAAP Financial Measures and Other Calculations” herein for a discussion of our definitions of FFO and AFFO.

(2)	FFO and AFFO are reduced by cash paid for preferred stock dividends.

(3)	Based on the diluted weighted-average common shares outstanding for the three months ended March 31, 2017 and 2016.

(4)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(2)	Adjusts the income tax provision to reflect our estimate of the cash taxes paid had we been a REIT for all periods presented, and is primarily comprised of foreign taxes. As a result income tax expense (benefit) is lower by the amount of the adjustment.

(3)	See "Definitions of Non-GAAP Measures and Other Calculations" herein for a discussion of our definitions of FFO and AFFO.

(4)	FFO and AFFO are reduced by cash paid for preferred stock dividends.

(5)	Based on the diluted weighted-average common shares outstanding for the twelve months ended December 31, 2016, 2015, 2014 and 2013..

(6)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(1)	The assumption for second quarter 2017 and full year 2017 diluted weighted-average common shares outstanding is based on diluted common shares outstanding as of March 31, 2017.

(2)	See “Definitions of Non-GAAP Financial Measures and Other Calculations” herein for a discussion of our definitions of FFO and AFFO.

(3)	The above reconciliation excludes line items included in our definition which are not applicable for the periods shown.

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(2)	The Net Debt to Last Quarter Annualized Adjusted EBITDA calculation does not give effect to a full quarter of ownership of FiberNet, as this acquisition closed on January 17, 2017.