NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

Quanta Services, Inc. (Quanta) is a leading provider of specialty contracting services, offering infrastructure solutions primarily to the electric power, oil and gas and communications industries in the United States, Canada and Australia and select other international markets. Quanta reports its results under two reportable segments: (1) Electric Power Infrastructure Services and (2) Oil and Gas Infrastructure Services.

Electric Power Infrastructure Services Segment

The Electric Power Infrastructure Services segment provides comprehensive network solutions to customers in the electric power industry. Services performed by the Electric Power Infrastructure Services segment generally include the design, installation, upgrade, repair and maintenance of electric power transmission and distribution infrastructure and substation facilities along with other engineering and technical services. This segment also provides emergency restoration services, including the repair of infrastructure damaged by inclement weather, the energized installation, maintenance and upgrade of electric power infrastructure utilizing unique bare hand and hot stick methods and Quanta’s proprietary robotic arm technologies, and the installation of “smart grid” technologies on electric power networks. In addition, this segment designs, installs and maintains renewable energy generation facilities, consisting of solar, wind and certain types of natural gas generation facilities, and related switchyards and transmission infrastructure. To a lesser extent, the segment also provides comprehensive communications infrastructure services to wireline, fiber and wireless carrier customers within the communications industry; services in connection with the construction of electric power generation facilities; the design, installation, maintenance and repair of commercial and industrial wiring; and the installation of traffic networks and cable and control systems for light rail lines.

Oil and Gas Infrastructure Services Segment

The Oil and Gas Infrastructure Services segment provides comprehensive network solutions to customers involved in the development and transportation of natural gas, oil and other pipeline products. Services performed by the Oil and Gas Infrastructure Services segment generally include the design, installation, repair and maintenance of pipeline transmission and distribution systems, gathering systems, production systems, storage systems and compressor and pump stations, as well as related trenching, directional boring and mechanized welding services. In addition, this segment’s services include pipeline protection, integrity testing, rehabilitation and replacement, and fabrication of pipeline support systems and related structures and facilities. Quanta also serves the offshore and inland water energy markets, primarily providing services to oil and gas exploration platforms, including mechanical installation (or “hook-ups”), electrical and instrumentation, pre-commissioning and commissioning, coatings, fabrication and marine asset repair. To a lesser extent, this segment designs, installs and maintains fueling systems, as well as water and sewer infrastructure. Through a recent acquisition discussed below, Quanta expanded its service offerings in this segment to include high-pressure and critical-path turnaround services to the downstream and midstream energy markets and enhanced its capabilities with respect to instrumentation and electrical services, piping, fabrication and storage tank services.

Acquisitions

On July 20, 2017, Quanta acquired Stronghold, Ltd. and Stronghold Specialty, Ltd. (collectively Stronghold), a specialized services business located in the United States that provides high-pressure and critical-path solutions to the downstream and midstream energy markets. The results of the acquired business are generally included in Quanta’s Oil and Gas Infrastructure Services segment and have been included in Quanta’s consolidated financial statements beginning on the date of acquisition.

During the nine months ended September 30, 2017, Quanta also completed two other acquisitions, which included a communications infrastructure services contractor and an electrical and communications contractor, both located in the United States. The results of these acquired businesses are generally included in Quanta’s Electric Power Infrastructure Services segment and have been included in Quanta’s consolidated financial statements beginning on the respective dates of acquisition.

During 2016 , Quanta completed five acquisitions. The results have been included in Quanta’s consolidated financial statements beginning on the respective dates of acquisition. See further discussion regarding these acquisitions in Note 4 .

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:

Principles of Consolidation

The condensed consolidated financial statements of Quanta include the accounts of Quanta Services, Inc. and its wholly owned subsidiaries, which are also referred to as its operating units. The condensed consolidated financial statements also include the accounts of certain of Quanta’s investments in joint ventures, which are either consolidated or proportionately consolidated, as discussed in the following summary of significant accounting policies. Investments in affiliated entities in which Quanta does not have a controlling financial interest, but over which Quanta has significant influence, usually because Quanta holds a voting interest of between 20% and 50%, are accounted for using the equity method. All significant intercompany accounts and transactions have been eliminated in consolidation. Unless the context requires otherwise, references to Quanta include Quanta Services, Inc. and its consolidated subsidiaries.

Interim Condensed Consolidated Financial Information

These unaudited condensed consolidated financial statements have been prepared pursuant to the rules of the U.S. Securities and Exchange Commission (SEC). Certain information and footnote disclosures, normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States (US GAAP), have been condensed or omitted pursuant to those rules and regulations. Quanta believes that the disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, necessary to fairly state the financial position, results of operations, comprehensive income and cash flows with respect to the interim condensed consolidated financial statements have been included. The results of operations and comprehensive income for the interim periods are not necessarily indicative of the results for the entire fiscal year. The results of Quanta have historically been subject to significant seasonal fluctuations.

Quanta recommends that these unaudited condensed consolidated financial statements be read in conjunction with the audited consolidated financial statements and notes thereto of Quanta and its consolidated subsidiaries included in Quanta’s Annual Report on Form 10-K for the year ended December 31, 2016 , which was filed with the SEC on March 1, 2017 .

Reclassifications

Quanta reclassified certain prior period amounts related to stock-based compensation on the condensed consolidated statements of cash flows to conform to the current period presentation under a recently adopted accounting update. Additionally, certain reclassifications have been made to the prior year’s condensed consolidated statements of operations to conform to classifications in the current year.

Use of Estimates and Assumptions

The preparation of financial statements in conformity with US GAAP requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities known to exist as of the date the financial statements are published, and the reported amounts of revenues and expenses recognized during the periods presented. Quanta reviews all significant estimates affecting its consolidated financial statements on a recurring basis and records the effect of any necessary adjustments prior to their publication. Judgments and estimates are based on Quanta’s beliefs and assumptions derived from information available at the time such judgments and estimates are made. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of financial statements. Estimates are primarily used in Quanta’s assessment of the allowance for doubtful accounts, valuation of inventory, useful lives of assets, fair value assumptions in analyzing goodwill, other intangibles and long-lived asset impairments, equity and other investments, loan receivables, purchase price allocations, acquisition-related contingent consideration, liabilities for self-insured and other claims and guarantees, multiemployer pension plan withdrawal liabilities, revenue recognition for construction contracts inclusive of contractual change orders and claims, share-based compensation, operating results of reportable segments, as well as the provision for income taxes and the calculation of uncertain tax positions.

Cash and Cash Equivalents

Quanta had cash and cash equivalents of $91.5 million and $112.2 million as of September 30, 2017 and December 31, 2016 . Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. Quanta considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents, which are carried at fair value. At September 30, 2017 and December 31, 2016 , cash equivalents were $8.3 million and $8.8 million , and consisted primarily of money market investments and money market mutual funds and are discussed further in Fair Value

Measurements below. As of September 30, 2017 and December 31, 2016 , cash and cash equivalents held in domestic bank accounts were $25.0 million and $19.5 million , and cash and cash equivalents held in foreign bank accounts were $66.5 million and $92.7 million . As of September 30, 2017 and December 31, 2016 , cash and cash equivalents held by Quanta’s investments in joint ventures, which are either consolidated or proportionately consolidated, were $34.0 million and $11.5 million , of which $10.0 million and $10.0 million related to domestic joint ventures. Cash and cash equivalents held by the joint ventures are available to support joint venture operations, but Quanta cannot utilize those assets to support its other operations. Quanta generally has no right to the joint ventures’ cash and cash equivalents other than participating in distributions and in the event of dissolution.

Current and Long-Term Accounts and Notes Receivable and Allowance for Doubtful Accounts

Quanta provides an allowance for doubtful accounts when collection of an account or note receivable is considered doubtful, and receivables are written off against the allowance when deemed uncollectible. Inherent in the assessment of the allowance for doubtful accounts are certain judgments and estimates regarding, among other factors, the customer’s access to capital, the customer’s willingness or ability to pay, general economic and market conditions, the ongoing relationship with the customer and uncertainties related to the resolution of disputed matters. Quanta considers accounts receivable delinquent after 30 days but does not generally include delinquent accounts in its analysis of the allowance for doubtful accounts unless the accounts receivable have been outstanding for at least 90 days. In addition to balances that have been outstanding for 90 days or more, Quanta also includes accounts receivable balances that relate to customers in bankruptcy or with other known difficulties in its analysis of the allowance for doubtful accounts. Material changes in customers’ business or cash flows, which may be impacted by negative economic and market conditions, could affect Quanta’s ability to collect amounts due from them. As of September 30, 2017 and December 31, 2016 , Quanta had allowances for doubtful accounts on current receivables of $5.1 million and $2.8 million . Long-term accounts receivable are included within other assets.

Should customers experience financial difficulties or file for bankruptcy, or should anticipated recoveries relating to receivables in existing bankruptcies or other workout situations fail to materialize, Quanta could experience reduced cash flows and losses in excess of current allowances provided.

The balances billed but not paid by customers pursuant to retainage provisions in certain contracts are generally due upon completion of the contracts and acceptance by the customer. Based on Quanta’s experience with similar contracts in recent years, the majority of the retainage balances at each balance sheet date are expected to be collected within the next twelve months. Current retainage balances as of September 30, 2017 and December 31, 2016 were $298.4 million and $231.0 million and were included in “Accounts receivable.” Retainage balances with settlement dates beyond the next twelve months were included in “Other assets, net,” and as of September 30, 2017 and December 31, 2016 were $26.8 million and $5.2 million .

Within accounts receivable, Quanta recognizes unbilled receivables in circumstances such as when revenues have been earned and recorded but the amount cannot be billed under the terms of the contract until a later date; costs have been incurred but are yet to be billed under cost-reimbursement type contracts; or amounts arise from routine lags in billing (for example, work completed one month but not billed until the next month). These balances do not include revenues accrued for work performed under fixed-price contracts as these amounts are recorded as costs and estimated earnings in excess of billings on uncompleted contracts. At September 30, 2017 and December 31, 2016 , the balances of unbilled receivables included in accounts receivable were $393.0 million and $206.8 million .

Goodwill and Other Intangibles

Quanta has recorded goodwill in connection with its historical acquisitions of companies. Upon acquisition, these companies were either combined into one of Quanta’s existing operating units or managed on a stand-alone basis as an individual operating unit. Goodwill recorded in connection with these acquisitions is subject to an annual assessment for impairment, which Quanta performs at the operating unit level for each operating unit that carries a balance of goodwill. Each of Quanta’s operating units is organized into one of two internal divisions: the Electric Power Infrastructure Services Division and the Oil and Gas Infrastructure Services Division. As most of the companies acquired by Quanta provide multiple types of services for multiple types of customers, these divisional designations are based on the predominant type of work performed by each operating unit at the point in time the divisional designation is made. Goodwill is required to be measured for impairment at the reporting unit level, which represents the operating segment level or one level below the operating segment level for which discrete financial information is available. Quanta has determined that its individual operating units represent its reporting units for the purpose of assessing goodwill impairments.

Quanta has the option to first assess qualitative factors to determine whether it is necessary to perform the two-step fair value-based impairment test described below. If Quanta believes that, as a result of its qualitative assessment, it is more likely

than not that the fair value of a reporting unit is less than its carrying amount, the quantitative impairment test is required. Quanta can choose to perform the qualitative assessment on none, some or all of its reporting units. Quanta can also bypass the qualitative assessment for any reporting unit in any period and proceed directly to step one of the impairment test, and then resume the qualitative assessment in any subsequent period. Qualitative indicators including deterioration in macroeconomic conditions, declining financial performance, or a sustained decrease in share price, among other things, may trigger the need for annual or interim impairment testing of goodwill associated with one or all of the reporting units.

Quanta’s goodwill impairment assessment is performed at year-end, or more frequently if events or circumstances arise which indicate that goodwill may be impaired. For instance, a decrease in Quanta’s market capitalization below book value, a significant change in business climate or loss of a significant customer, as well as the qualitative indicators referenced above, may trigger the need for interim impairment testing of goodwill for one or all of its reporting units. The first step of the two-step fair value based test involves comparing the fair value of each of Quanta’s reporting units with its carrying value, including goodwill. If the carrying value of the reporting unit exceeds its fair value, the second step is performed. The second step compares the carrying amount of the reporting unit’s goodwill to the implied fair value of its goodwill. If the implied fair value of goodwill is less than the carrying amount, an impairment loss would be recorded as a reduction to goodwill with a corresponding charge to operating expense.

Quanta determines the fair value of its reporting units using a weighted combination of the discounted cash flow, market multiple and market capitalization valuation approaches, with heavier weighting on the discounted cash flow method, as in management’s opinion, this method currently results in the most accurate calculation of a reporting unit’s fair value. Determining the fair value of a reporting unit requires judgment and the use of significant estimates and assumptions. Such estimates and assumptions include, among others, revenue growth rates, operating margins, discount rates, weighted average costs of capital and future market conditions. Quanta believes the estimates and assumptions used in its impairment assessments are reasonable and based on available market information, but variations in any of the assumptions could result in materially different calculations of fair value and determinations of whether or not an impairment is indicated.

Under the discounted cash flow method, Quanta determines fair value based on the estimated future cash flows of each reporting unit, discounted to present value using risk-adjusted industry discount rates, which reflect the overall level of inherent risk of a reporting unit and the rate of return an outside investor would expect to earn. Cash flow projections are derived from budgeted amounts and operating forecasts (typically a one-year model) plus an estimate of later period cash flows, all of which are evaluated by management. Subsequent period cash flows are developed for each reporting unit using growth rates that management believes are reasonably likely to occur, along with a terminal value derived from the reporting unit’s earnings before interest, taxes, depreciation and amortization (EBITDA). The EBITDA multiples for each reporting unit are based on trailing twelve-month comparable industry data.

Under the market multiple and market capitalization approaches, Quanta determines the estimated fair value of each of its reporting units by applying transaction multiples to each reporting unit’s projected EBITDA and then averaging that estimate with similar historical calculations using either a one, two or three year average. For the market capitalization approach, Quanta adds a reasonable control premium, which is estimated as the premium that would be received in a sale of the reporting unit in an orderly transaction between market participants.

For recently acquired reporting units, a step one impairment test may indicate an implied fair value that is substantially similar to the reporting unit’s carrying value. Such similarities in value are generally an indication that management’s estimates of future cash flows associated with the recently acquired reporting unit remain relatively consistent with the assumptions that were used to derive its initial fair value.

During the fourth quarter of 2016 , a two-step fair-value based goodwill impairment analysis was performed for each of Quanta’s reporting units, and no reporting units were evaluated solely on a qualitative basis. Step one of the analysis indicated that the implied fair value of each of Quanta’s reporting units, other than recently acquired reporting units and the reporting units that recorded goodwill impairment charges in 2015, was substantially in excess of its carrying value.

As discussed generally above, when evaluating the 2016 step one impairment test results, management considered many factors in determining whether or not an impairment of goodwill for any reporting unit was reasonably likely to occur in future periods, including future market conditions and the economic environment in which Quanta’s reporting units were operating. Additionally, management considered the sensitivity of its fair value estimates to changes in certain valuation assumptions. After taking into account a 10% decrease in the fair value of each of Quanta’s reporting units, two reporting units within Quanta’s Oil and Gas Infrastructure Division had fair values below their respective carrying values. Quanta recorded asset impairment charges

for these reporting units in 2015. The fair values determined in 2016 for these reporting units were consistent with the fair values determined in 2015 and approximated their current carrying values, and therefore no impairment was required. Circumstances such as market declines, unfavorable economic conditions, loss of a major customer or other factors could increase the risk of impairment of goodwill for these reporting units in future periods.

If an operating unit experiences prolonged periods of declining revenues, operating margins or both, it may be at risk of failing step one of the goodwill impairment test. Certain operating units have experienced declines over the short-term due to challenging macroeconomic conditions in certain geographic areas and low oil and natural gas prices, which have negatively impacted customer spending and resulted in project cancellations and delays. Additionally, customer capital spending has been constrained as a result of an increasingly complex regulatory and permitting environment. Certain operating units within Quanta’s Oil and Gas Infrastructure Services Division that primarily operate within the midstream and smaller-scale transmission market have continued to be negatively impacted by these factors. Goodwill and intangible assets associated with these operating units were $72.2 million and $11.5 million at September 30, 2017 . Quanta monitors these conditions and others to determine if it is necessary to perform step one of the fair-value based impairment test for one or more operating units prior to the annual impairment assessment. No interim impairment charges were recorded during the nine months ended September 30, 2017 . Although Quanta is not aware of circumstances that would lead to a goodwill impairment at a reporting unit currently, circumstances such as a continued market decline, the loss of a major customer or other factors could impact the valuation of goodwill in the future.

Quanta’s intangible assets include customer relationships, backlog, trade names, non-compete agreements, patented rights and developed technology, all subject to amortization. The value of customer relationships is estimated as of the date a business is acquired based on the value-in-use concept utilizing the income approach, specifically the excess earnings method. This analysis consists of discounting to present value the projected cash flows attributable to the customer relationships, with consideration given to customer contract renewals and estimated customer attrition rates, the importance of existing customer relationships to Quanta’s business plan, income taxes and required rates of return. Quanta values backlog for acquired businesses as of the acquisition date based upon the contractual nature of the backlog within each service line, discounted to present value. The value of trade names is estimated using the relief-from-royalty method of the income approach. This approach is based on the assumption that in lieu of ownership, a company would be willing to pay a royalty for use of the trade name.

Quanta amortizes intangible assets based upon the estimated consumption of their economic benefits, or on a straight-line basis if the pattern of economic benefit cannot otherwise be reliably estimated. Intangible assets subject to amortization are reviewed for impairment and are tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. For instance, a significant change in business climate or a loss of a significant customer, among other things, may trigger the need for interim impairment testing of intangible assets. An impairment loss would be recognized if the carrying amount of an intangible asset is not recoverable and its carrying amount exceeds its fair value.

Investments in Affiliates and Other Entities

In the normal course of business, Quanta enters into various types of investment arrangements, each having unique terms and conditions. These investments may include equity interests held by Quanta in business entities, including general or limited partnerships, contractual joint ventures, or other forms of equity or profit participation. These investments may also include Quanta’s participation in different financing structures, such as the extension of loans to project specific entities, the acquisition of convertible notes issued by project specific entities, or other strategic financing arrangements. Quanta also enters into strategic partnerships with customers and infrastructure investors to provide fully integrated infrastructure services on certain projects, including planning and feasibility analyses, engineering, design, procurement, construction and project operation and maintenance. These projects include public-private partnerships, private infrastructure projects and concessions, along with build, own, operate and transfer and build to suit arrangements. As part of this strategy, during the nine months ended September 30, 2017, Quanta formed a partnership with select investors that provides $1.0 billion of capital, including $80.0 million from Quanta, available to invest in certain of these infrastructure projects through July 1, 2024. Wholly owned subsidiaries of Quanta serve as the general partner of this partnership and as an independently operated registered investment adviser that manages the invested capital.

Quanta determines whether investments involve a variable interest entity (VIE) based on the characteristics of the subject entity. If the entity is determined to be a VIE, then management determines if Quanta is the primary beneficiary of the entity and whether or not consolidation of the VIE is required. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the activities that most significantly affect the VIE’s economic performance and (ii) the obligation to absorb significant losses of, or the right to receive significant benefits from, the VIE. When Quanta is deemed to be the primary beneficiary, the VIE is consolidated and the other party’s equity interest in the VIE is accounted for as a non-controlling interest. In cases where Quanta determines that it has an undivided interest in the assets, liabilities, revenues and profits of an unincorporated VIE (e.g., a general partnership interest), such amounts are consolidated on a basis proportional to Quanta’s ownership interest in the

unincorporated entity.

Investments in entities of which Quanta is not the primary beneficiary, but over which Quanta has the ability to exercise significant influence, are accounted for using the equity method of accounting. Quanta’s share of net income or losses from unconsolidated equity investments is reported as equity in earnings (losses) of unconsolidated affiliates, which is included in “Other income (expense)” in the condensed consolidated statements of operations. Equity investments are reviewed for impairment by assessing whether any decline in the fair value of the investment below the carrying value is other than temporary. In making this determination, factors such as the ability to recover the carrying amount of the investment and the inability of the investee to sustain an earnings capacity are evaluated in determining whether a loss in value should be recognized. Any impairment losses related to investments would be recognized in equity in earnings (losses) of unconsolidated affiliates. Equity method investments are carried at original cost and are included in “Other assets, net” in the condensed consolidated balance sheets and are adjusted for Quanta’s proportionate share of the investees’ income, losses and distributions.

Quanta has a minority ownership interest in a limited partnership that was selected during 2014 to build, own and operate a new electric transmission line and two substations in Alberta, Canada. The limited partnership contracted with a Quanta subsidiary to perform the engineering, procurement and construction (EPC) services for the project, and the Quanta subsidiary recognizes revenue and related cost of services as performance progresses on the project. However, due to Quanta’s ownership interest, a proportional amount of the EPC profit is deferred until the electric transmission line and related substations are constructed and ownership of the assets is deemed to be transferred to the third party customer. The profit deferral has been recorded as a decrease to the equity method investment included in “Other assets, net” in the accompanying condensed consolidated balance sheets and as a component of equity in earnings (losses) of unconsolidated affiliates, which is included in “Other income (expense)” in the condensed consolidated statements of operations. See Notes 8 and 10 for additional disclosures related to investments.

Revenue Recognition

Quanta provides its services pursuant to master service agreements, repair and maintenance contracts and fixed price and non-fixed price installation contracts. Pricing under these contracts may be competitive unit price, cost-plus/hourly (or time and materials basis) or fixed price (or lump sum basis), and the final terms and prices of these contracts are frequently negotiated with the customer. Under unit-based contracts, the utilization of an output-based measurement is appropriate for revenue recognition, and Quanta recognizes revenue as units are completed based on pricing established with the customer for each delivered unit, which best reflects the pattern in which the obligation to the customer is fulfilled. Under cost-plus/hourly and time and materials type contracts, Quanta recognizes revenue on an input basis, as labor hours are incurred and services are performed.

Revenues from fixed price contracts are recognized using the percentage-of-completion method, measured by the percentage of costs incurred to date to total estimated costs for each contract. Such contracts provide that the customer accept completion of progress to date and compensate Quanta for services rendered, which may be measured in terms of units installed, hours expended, costs incurred to date compared to total estimated contract costs or some other measure of progress. Contract costs include all direct materials, labor and subcontract costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and depreciation costs. Much of the material associated with Quanta’s work is owner-furnished and is therefore not included in contract revenues and costs. The cost estimation process is based on professional knowledge and experience of Quanta’s engineers, project managers and financial professionals. Changes in job performance, job conditions and final contract settlements are factors that influence management’s assessment of contract value and estimated costs, and as a result, the profit recognized.

Actual revenues and project costs can vary, sometimes substantially, from previous estimates due to changes in a variety of factors including unforeseen circumstances not included in Quanta’s cost estimates or covered by its contracts for which it cannot obtain adequate compensation, including concealed or unknown environmental conditions; changes in the cost of equipment, commodities, materials or labor; unanticipated costs or claims due to customer-caused delays, customer failure to provide required materials or equipment, errors in engineering, specifications or designs, project modifications, or contract termination and Quanta’s inability to obtain reimbursement for such costs or recover on such claims; weather conditions; and quality issues requiring rework or replacement. These factors, along with other risks inherent in performing fixed price contracts may cause actual revenues and gross profits for a project to differ from previous estimates and could result in reduced profitability or losses on projects. Changes in these factors may result in revisions to costs and income, and their effects are recognized in the period in which the revisions are determined. These factors are routinely evaluated on a project-by-project basis throughout the project term, and the impact of corresponding revisions in management’s estimates of contract value, contract cost and contract profit are recorded as necessary in the period in which the revisions are determined. Provisions for losses on uncompleted contracts are made in the period in which such losses are determined to be probable and the amount can be reasonably estimated.

Quanta’s operating results for the three and nine months ended September 30, 2017 were impacted by less than 5% as a result of aggregate changes in contract estimates related to projects that were in progress at the beginning of the respective periods. Quanta’s operating results for the three months ended September 30, 2016 were positively impacted by 6.3% as a result of aggregate changes in contract estimates related to projects that were in progress at June 30, 2016 , primarily due to the aggregate positive impact of numerous individually immaterial changes in estimates, which was generally due to better than expected performance. Quanta’s operating results for the nine months ended September 30, 2016 were impacted by less than 5% as a result of aggregate changes in contract estimates related to projects that were in progress at December 31, 2015 . However, operating results for the three and nine months ended September 30, 2016 included losses of $3.0 million and $54.8 million on a power plant construction project in Alaska due to performance issues that increased the estimated costs of the project. This project was substantially completed during the fourth quarter of 2016. The losses on this project were partially offset by the aggregate positive impact of numerous individually immaterial changes in profitability generally due to better than expected performance on projects that were in progress at December 31, 2015 .

The current asset “Costs and estimated earnings in excess of billings on uncompleted contracts” represents revenues recognized in excess of amounts billed for contracts accounted for under the percentage-of-completion method. The current liability “Billings in excess of costs and estimated earnings on uncompleted contracts” represents billings in excess of revenues recognized for contracts accounted for under the percentage-of-completion method.

Quanta may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Quanta determines the probability that such costs will be recovered based upon evidence such as past practices with the customer, specific discussions or preliminary negotiations with the customer or verbal approvals. Quanta treats items as costs of contract performance in the period incurred if it is not probable that the costs will be recovered or will recognize revenue if it is probable that the contract price will be adjusted and can be reliably estimated.

As of September 30, 2017 and December 31, 2016 , Quanta recognized revenues of $115.5 million and $137.8 million related to change orders and/or claims that were in the process of being negotiated in the normal course of business.

These aggregate contract price adjustments represent management’s best estimate of additional contract revenues which have been earned and which management believes are probable of collection. The amounts ultimately realized by Quanta upon final acceptance by its customers could be higher or lower than such estimated amounts; however, such amounts cannot currently be estimated.

Income Taxes

Quanta follows the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recorded for future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the underlying assets or liabilities are recovered or settled.

Quanta regularly evaluates valuation allowances established for deferred tax assets for which future realization is uncertain. The estimation of required valuation allowances includes estimates of future taxable income. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Quanta considers projected future taxable income and tax planning strategies in making this assessment. If actual future taxable income differs from these estimates, Quanta may not realize deferred tax assets to the extent estimated.

Quanta records reserves for income taxes related to certain tax positions in those instances where Quanta considers it more likely than not that additional taxes may be due in excess of amounts reflected on income tax returns filed. When recording reserves for expected tax consequences of uncertain positions, Quanta assumes that taxing authorities have full knowledge of the position and all relevant facts. Quanta continually reviews exposure to additional tax obligations, and as further information is known or events occur, changes in tax reserves may be recorded. To the extent interest and penalties may be assessed by taxing authorities on any underpayment of income tax, such amounts have been accrued and included in the provision for income taxes.

As of September 30, 2017 , the total amount of unrecognized tax benefits relating to uncertain tax positions was $31.8 million , a decrease from December 31, 2016 of $3.4 million . This decrease in unrecognized tax benefits resulted primarily from a $6.2 million decrease in reserves for uncertain tax positions resulting from the expiration of statute of limitations periods, partially offset by tax positions to be taken for 2017 . Although the Internal Revenue Service completed its examination related to tax years 2010, 2011 and 2012 during the year ended December 31, 2016 , certain subsidiaries remain under examination by various U.S. state, Canadian and other foreign tax authorities for multiple periods. Quanta believes it is reasonably possible that within the next 12 months unrecognized tax benefits may decrease by up to $13.7 million as a result of settlement of these examinations or as a

result of the expiration of certain statute of limitations periods.

U.S. federal and state and foreign income tax laws and regulations are voluminous and are often ambiguous. As such, Quanta is required to make many subjective assumptions and judgments regarding its tax positions that could materially affect amounts recognized in its future consolidated balance sheets, consolidated statements of operations and consolidated statements of comprehensive income.

Earnings Per Share

Basic and diluted earnings per share attributable to common stock are computed using the weighted average number of common shares outstanding during the periods. Exchangeable shares that were issued pursuant to certain of Quanta’s historical acquisitions (as further discussed in Note 8), which are exchangeable on a one-for-one basis with shares of Quanta common stock, have been included in the calculation of weighted average shares outstanding for basic and diluted earnings per share attributable to common stock for the portion of the periods that they were outstanding. Additionally, unvested stock-based awards that contain non-forfeitable rights to dividends or dividend equivalents (participating) have been included in the calculation of basic and diluted earnings per share attributable to common stock for the portion of the periods that they were outstanding. Diluted earnings per share attributable to common stock is computed using the weighted average number of common shares outstanding during the period adjusted for all potentially dilutive common stock equivalents, except in cases where the effect of the common stock equivalents would be antidilutive.

Self-Insurance

Quanta is insured for employer’s liability, workers’ compensation, auto liability and general liability claims. Under these programs, the deductible for employer’s liability is $1.0 million per occurrence, the deductible for workers’ compensation is $5.0 million per occurrence, and the deductibles for auto liability and general liability are $10.0 million per occurrence. Quanta is generally self-insured for all claims that do not exceed the amount of the applicable deductible. Quanta also has employee health care benefit plans for most employees not subject to collective bargaining agreements, of which the primary plan is subject to a deductible of $0.4 million per claimant per year.

Losses under all of these insurance programs are accrued based upon Quanta’s estimate of the ultimate liability for claims reported and an estimate of claims incurred but not reported, with assistance from third-party actuaries. These insurance liabilities are difficult to assess and estimate due to unknown factors, including the severity of an injury, the extent of damage, the determination of Quanta’s liability in proportion to other parties and the number of incidents not reported. The accruals are based upon known facts and historical trends, and management believes such accruals are adequate.

Collective Bargaining Agreements

Some of Quanta’s operating units are parties to various collective bargaining agreements with unions that represent certain of their employees. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to those in the expiring agreements. The agreements require the operating units to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multiemployer pension plans and employee benefit trusts. Quanta’s multiemployer pension plan contribution rates generally are specified in the collective bargaining agreements (usually on an annual basis), and contributions are made to the plans on a “pay-as-you-go” basis based on its union employee payrolls. The location and number of union employees that Quanta employs at any given time and the plans in which they may participate vary depending on the projects Quanta has ongoing at that time and the need for union resources in connection with those projects. Therefore, Quanta is unable to accurately predict the union employee payroll and the amount of the resulting multiemployer pension plan contribution obligation for future periods.

Stock-Based Compensation

Quanta recognizes compensation expense for restricted stock, restricted stock units (RSUs) and performance units to be settled in common stock based on the fair value of the awards at the date of grant, net of estimated forfeitures. The fair value of these awards is generally determined based on the number of shares or units granted and the closing price of Quanta’s common stock on the date of grant; however, the fair value of performance units with market-based metrics is determined using a Monte Carlo simulation valuation methodology. An estimate of future forfeitures, based on historical data, is utilized to determine the period expense. Such estimates are subject to change and may impact the value that will ultimately be recognized as compensation expense. The resulting compensation expense for performance unit and time-based RSU awards is recognized on a straight-line basis over the requisite service period, which is generally the vesting period, and the resulting compensation expense for performance-based RSU awards is recognized using the graded vesting method over the requisite service period. The compensation

expense related to performance units can also vary from period to period based on changes in the total number of performance units that Quanta anticipates will vest. Payments made by Quanta to satisfy employee tax withholding obligations associated with awards settled in common stock are classified as financing cash flows.

Compensation expense associated with liability-based awards, such as RSUs that are expected to or may settle in cash, is recognized based on a remeasurement of the fair value of the award at the end of each reporting period. Upon settlement, the holders receive for each RSU an amount in cash equal to the fair market value on the settlement date of one share of Quanta common stock, as specified in the applicable award agreement. For additional information on Quanta’s restricted stock, RSU and performance unit awards, see Note 9.

Functional Currency and Translation of Financial Statements

The U.S. dollar is the functional currency for the majority of Quanta’s operations, which are primarily located within the United States. The functional currency for Quanta’s foreign operations, which are primarily located in Canada and Australia, is typically the currency of the country where the foreign operating unit is located and transacts the majority of its activities, including billings, financing, payroll and other expenditures. The treatment of foreign currency translation gains or losses is dependent upon management’s determination of the functional currency, and when preparing the consolidated financial statements, Quanta translates the financial statements of its foreign operating units from their functional currency into U.S. dollars. Statements of operations, comprehensive income and cash flows are translated at average monthly rates, while balance sheets are translated at month-end exchange rates. The translation of the balance sheet results in translation gains or losses, which are included as a separate component of equity under “Accumulated other comprehensive income (loss).” Gains and losses arising from transactions not denominated in functional currencies are included within “Other income (expense)” in the condensed consolidated statements of operations.

Comprehensive Income

Components of comprehensive income include all changes in equity during a period except those resulting from changes in Quanta’s capital-related accounts. Quanta records other comprehensive income (loss) for foreign currency translation adjustments related to its foreign operations and for other revenues, expenses, gains and losses that are included in comprehensive income but excluded from net income.

Litigation Costs and Reserves

Quanta records reserves when the likelihood of incurring a loss is probable and the amount of loss can be reasonably estimated. Costs incurred for litigation are expensed as incurred. Further details are presented in Note 10.

Fair Value Measurements

For disclosure purposes, qualifying assets and liabilities are categorized into three broad levels based on the priority of the inputs used to determine their fair values. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). Certain assumptions and other information as they relate to these qualifying assets and liabilities are described below.

Contingent Consideration Liabilities. As of September 30, 2017 and December 31, 2016 , financial instruments required to be measured at fair value on a recurring basis consisted primarily of Quanta’s acquisition-related contingent consideration liabilities, which represent the estimated fair value of future amounts payable to the former owners of acquired businesses. Payment of such consideration is contingent on the future financial performance of the acquired businesses, and the fair value of such consideration is estimated by management based on entity-specific assumptions that are evaluated on an ongoing basis. As of September 30, 2017 and December 31, 2016 , the fair value of these contingent consideration liabilities totaled $70.9 million and $19.5 million , all of which was included in “Insurance and other non-current liabilities” on Quanta’s condensed consolidated balance sheet and none of which was earned as of such dates.

The fair values of the contingent consideration liabilities as of September 30, 2017 were determined using a Monte Carlo simulation valuation methodology based on probability-weighted financial performance projections and other inputs, including a discount rate and an expected volatility factor for each acquisition. The discount rates ranged from 1.1% to 1.8% depending on the settlement methods available and are generally based on a risk-free rate and/or Quanta’s cost of debt. The expected volatility factors ranged from 25.0% to 29.6% based on historical asset volatility of selected guideline public companies. The fair value determinations incorporate significant inputs not observable in the market. Accordingly, the level of inputs used for these fair value measurements is the lowest level (Level 3). Significant changes in any of these assumptions could result in a significantly higher or lower potential liability. Quanta expects a significant portion of these liabilities to be settled by late 2020 or early 2021.

The majority of Quanta’s contingent consideration liabilities are subject to a maximum payment amount, which aggregated to $139.5 million as of September 30, 2017 . One contingent consideration liability is not subject to a maximum payout amount, and the fair value of that liability was $1.0 million as of September 30, 2017 .

Quanta’s aggregate contingent consideration liabilities can change due to additional business acquisitions, payments to settle outstanding liabilities, changes in the fair value of amounts owed, and foreign currency translation gains or losses. During the three and nine months ended September 30, 2017 , the acquisition of Stronghold increased Quanta’s contingent consideration liabilities by $51.1 million . During the three and nine months ended September 30, 2016 , acquisitions increased Quanta’s contingent consideration liabilities by $3.3 million and $18.7 million . Quanta made no payments related to contingent consideration during the three and nine months ended September 30, 2017 and no payments and a nominal payment during the three and nine months ended September 30, 2016 . Fair value adjustments will be reflected in operating income on Quanta’s condensed consolidated statements of operations. No changes in the fair value of Quanta’s contingent consideration liabilities have occurred during the three and nine months ended September 30, 2017 and 2016 .

Intangible Assets. In connection with Quanta’s acquisitions, identifiable intangible assets acquired typically include goodwill, backlog, customer relationships, trade names, covenants not-to-compete, patented rights and developed technology. Quanta utilizes the fair value premise as the primary basis for its valuation procedures, which is a market-based approach to determine the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Quanta periodically engages the services of an independent valuation firm when a new business is acquired to assist management with this valuation process, including assistance with the selection of appropriate valuation methodologies and the development of market-based valuation assumptions. Based on these considerations, management utilizes various valuation methods, including an income approach, a market approach and a cost approach, to determine the fair value of intangible assets acquired based on the appropriateness of each method in relation to the type of asset being valued. The assumptions used in these valuation methods are analyzed and compared, where possible, to available market data, such as industry-based weighted average costs of capital and discount rates, trade name royalty rates, public company valuation multiples and recent market acquisition multiples. In accordance with its annual impairment test during the quarter ended December 31, 2016 , the carrying amounts of such assets, including goodwill, were compared to their fair values. The level of inputs used for these fair value measurements is the lowest level (Level 3). Quanta uses the assistance of third party specialists to develop valuation assumptions. Quanta believes that these valuation methods appropriately represent the methods that would be used by other market participants in determining fair value.

Investments and Financing Instruments. Quanta also uses fair value measurements in connection with the valuation of its investments in private company equity interests and financing instruments. These valuations require significant management judgment due to the absence of quoted market prices, the inherent lack of liquidity and the long-term nature of such assets. Typically, the initial costs of these investments are considered to represent fair market value, as such amounts are negotiated between willing market participants. On a quarterly basis, Quanta performs an evaluation of its investments to determine if an other-than-temporary decline in the value of each investment has occurred and whether the recorded amount of each investment will be realizable. If an other-than-temporary decline in the value of an investment occurs, a fair value analysis would be performed to determine the degree to which the investment was impaired and a corresponding charge to earnings would be recorded during the period. These types of fair market value assessments are similar to other nonrecurring fair value measures used by Quanta, which include the use of significant judgment and available relevant market data. Such market data may include observations of the valuation of comparable companies, risk adjusted discount rates and an evaluation of the expected performance of the underlying portfolio asset, including historical and projected levels of profitability or cash flows. In addition, a variety of additional factors may be reviewed by management, including, but not limited to, contemporaneous financing and sales transactions with third parties, changes in market outlook and the third-party financing environment.

Other. The carrying values of cash equivalents, accounts receivable and accounts payable and accrued expenses approximate fair value due to the short-term nature of these instruments. The carrying value of variable rate debt also approximates fair value. All of Quanta’s cash equivalents were categorized as Level 1 assets at September 30, 2017 and December 31, 2016 , as all values were based on unadjusted quoted prices for identical assets in an active market that Quanta has the ability to access.

Adoption of New Accounting Pronouncements

In July 2015 , the FASB issued an update that requires inventory to be measured at the lower of either cost or net realizable value. When evidence exists that the net realizable value of inventory is lower than its cost, the difference will be recognized as a loss in earnings in the period in which it occurs. Quanta adopted this guidance effective January 1, 2017 , and the adoption of the update did not have a significant impact on Quanta’s consolidated financial statements or related disclosures.

In March 2016 , the FASB issued an update that amends the accounting for share-based payments in several key areas, including the treatment and cash flow presentation of tax effects related to the settlement of share-based payments and the accounting for forfeitures of share-based awards. The new guidance requires companies with share-based payments to record all related tax effects at settlement (or expiration) through income tax expense on the statement of operations rather than through additional paid-in capital (APIC) within equity. This update also requires excess tax benefits to be classified as an operating activity on the statement of cash flows rather than reclassified as a financing activity and requires cash paid by an employer when withholding shares for the employee portion of taxes to be presented as a financing activity. The update also allows companies to either account for forfeitures of share-based payments as they occur or to estimate forfeitures. This guidance is required to be applied prospectively except for the classification of cash related to tax withholding, which requires retrospective application. Quanta adopted this guidance effective January 1, 2017 and will continue to estimate forfeitures of share-based payments. Quanta anticipates increased volatility of income tax expense after adoption of this guidance, and during the three and nine months ended September 30, 2017 recorded income tax benefits of $0.1 million and $5.1 million related to the settlement of share-based awards. APIC was not adjusted for amounts recorded prior to 2017, and therefore Quanta’s retained earnings were not affected by the adoption of this guidance. Additionally, $0.3 million and $7.5 million were reclassified from operating activities to financing activities on the statements of cash flows for the three and nine months ended September 30, 2016 associated with cash paid by Quanta to satisfy tax withholding obligations for share-settled awards. Further, the presentation of excess tax benefits on the statements of cash flows is now shown as cash flows from operating activities rather than in financing activities. The excess tax benefits reclassified to operating activities for the three and nine months ended September 30, 2016 were $0.5 million and $0.7 million .

In October 2016 , the FASB issued an update that amends the consolidation guidance related to how a reporting entity that is the single decision maker of a VIE should treat indirect interests in the VIE held through related parties that are under common control with the reporting entity when determining whether it is the primary beneficiary of a VIE. A reporting entity has an indirect interest in a VIE if it has a direct interest in a related party that, in turn, has a direct interest in the VIE. Quanta adopted this guidance on January 1, 2017 , and the adoption of the update did not have a significant impact on its consolidated financial statements or related disclosures.

Accounting Standards Not Yet Adopted

In May 2014 , the FASB issued an update that supersedes most current revenue recognition guidance, as well as some cost recognition guidance. The update requires that the recognition of revenue related to the transfer of goods or services to customers reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires new qualitative and quantitative disclosures about the nature, amount, timing and uncertainty of revenues and cash flows arising from customer contracts, including significant judgments and changes in judgments, information about contract balances and performance obligations, and assets recognized from costs incurred to obtain or fulfill a contract. The new guidance is effective for fiscal years beginning on or after December 15, 2017 and can be applied on a full retrospective or modified retrospective basis, whereby the entity records a cumulative effect of initially applying this update at the date of initial application.

Quanta is currently evaluating the potential impact of this update on its consolidated financial statements and is planning to adopt the update using the modified retrospective transition method effective January 1, 2018 , which will result in a cumulative-effect adjustment recorded in retained earnings. Quanta has evaluated the impact of this update on a sample of contracts expected to be representative of the population of contracts that will generate revenues in 2018 and based on the sample results does not expect the update to materially affect its results of operations, financial position or cash flows. Quanta has begun evaluating the impact of this update on the remainder of its contracts that are anticipated to generate revenues in 2018 and is in the process of implementing changes to its processes and controls to meet the reporting and disclosure requirements of this update. 

In January 2016 , the FASB issued an update that addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments to provide users of financial statements with more decision-useful information. The new standard is effective for interim and annual periods beginning after December 15, 2017 . Quanta is evaluating the impact of the new standard on its consolidated financial statements and will adopt the new standard by January 1, 2018 .

In February 2016 , the FASB issued an update that requires companies to recognize on the balance sheet the contractual right to use assets and liabilities corresponding to the rights and obligations created by lease contracts. The new standard is effective for interim and annual periods beginning after December 15, 2018 . While Quanta continues to evaluate the effect of the standard on its consolidated financial statements, it is anticipated that the adoption of the standard will materially impact its statement of financial position.

In June 2016 , the FASB issued an update that will change the way companies measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The update will require companies to use an

“expected loss” model for instruments measured at amortized cost and to record allowances for available-for-sale debt securities rather than reduce the carrying amounts. The update will also require disclosure of information regarding how a company developed its allowance, including changes in the factors that influenced management’s estimate of expected credit losses and the reasons for those changes. Companies will apply this standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The new standard is effective for interim and annual reporting periods beginning after December 15, 2019 . Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2020 .

In August 2016 , the FASB issued an update intended to standardize the classification of certain transactions on the statement of cash flows . These transactions include contingent consideration payments made after a business combination, proceeds from the settlement of corporate-owned life insurance policies and distributions received from equity method investments. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 and requires application using a retrospective transition method. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 .

In October 2016 , the FASB issued an update that will require a reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. Any deferred tax asset that arises in the buyer’s jurisdiction would also be recognized at the time of the transfer. The new guidance will not apply to intra-entity transfers of inventory. The income tax consequences from the sale of inventory from one member of a consolidated entity to another will continue to be deferred until the inventory is sold to a third party. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 . The modified retrospective method will be required for transition to the new guidance, with a cumulative-effect adjustment recorded in retained earnings as of the beginning of the period of adoption. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 .

In November 2016 , the FASB issued an update intended to standardize the classification of restricted cash and cash equivalents transactions on the statement of cash flows . The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 . The retrospective transition method will be required for this new guidance. Quanta is currently evaluating the impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 .

In January 2017 , the FASB issued an update intended to clarify whether transactions should be accounted for as acquisitions or disposals of assets or businesses. When substantially all of the fair value of the gross assets acquired or disposed of is concentrated in a single identifiable asset or group of similar identifiable assets, the asset or group is not a business. The update will require, among other things, that to be considered a business, a set of assets and activities must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output. Additionally, the update will remove the evaluation of whether a market participant could replace missing elements in order to consider the set of assets and activities a business, will provide more stringent criteria for sets without outputs and will narrow the definition of output. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 and the prospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 .

Also in January 2017 , the FASB issued an update intended to simplify the subsequent measurement of goodwill by eliminating the second step in the current two-step goodwill impairment test. The update will require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, if applicable. Additionally, the update will eliminate the requirement that a reporting unit with a zero or negative carrying amount perform a qualitative assessment and the second step of the two-step goodwill impairment test and will instead require disclosure of the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount of net assets. This update is effective for interim and annual reporting periods beginning after December 15, 2019 . The prospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2020 .

In May 2017 , the FASB issued an update providing guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. A modification should be accounted for unless the following characteristics of the award are unchanged: the fair value, the vesting conditions and the classification as an equity instrument or a liability instrument. The update is effective for interim and annual periods beginning after December 15, 2017 and

is required to be applied prospectively. Quanta is evaluating the impact of the new accounting standard on its consolidated financial statements and will adopt the new standard by January 1, 2018 .

In August 2017 , the FASB issued an update which amends and simplifies existing guidance for presenting the economic effects of risk management activities in the financial statements. The update is effective for interim and annual periods beginning after December 15, 2018 . The amended presentation and disclosure guidance is required only prospectively, but certain amendments, if applicable, could require a cumulative-effect adjustment. Quanta is evaluating the impact of this new standard on its consolidated financial statements and will adopt the new standard by January 1, 2019 ; however, as of September 30, 2017 , Quanta had no hedging relationships outstanding.

On July 20, 2017, Quanta acquired Stronghold, a specialized services business located in the United States that provides high-pressure and critical-path solutions to the downstream and midstream energy markets. The aggregate consideration paid at closing for this acquisition was $360.0 million in cash and 2,693,680 shares of Quanta common stock, which had a fair value of approximately $81.3 million at the date of acquisition. Additionally, the acquisition includes the potential payment of up to $100.0 million of contingent consideration, payable if the acquired business achieves certain financial targets over a three -year period. Based on the estimated fair value of this contingent consideration, Quanta recorded a $51.1 million liability as of the date of acquisition. The results of the acquired business have generally been included in Quanta’s Oil and Gas Infrastructure Services segment and consolidated financial statements since the date of acquisition.

During the nine months ended September 30, 2017, Quanta also completed two other acquisitions, which included a communications infrastructure services contractor and an electrical and communications contractor, both located in the United States. The aggregate consideration for these acquisitions consisted of $11.9 million paid or payable in cash, subject to certain adjustments, and 288,666 shares of Quanta common stock, with a value of $8.3 million as of the respective acquisition dates. The results of the acquired businesses have generally been included in Quanta’s Electric Power Infrastructure Services segment and consolidated financial statements since the respective dates of acquisition.

During 2016 , Quanta completed five acquisitions. The results of four of the acquired companies are generally included in Quanta’s Electric Power Infrastructure Services segment. These companies included an electrical infrastructure services company located in Australia, a utility contracting company located in Canada, a full service medium- and high-voltage powerline contracting company located in the United States and a communications services company located in Canada. Quanta also acquired a pipeline service contractor located in the United States, the results of which are generally included in Quanta’s Oil and Gas Infrastructure Services segment. The aggregate consideration for these acquisitions consisted of $75.9 million paid or payable in cash, subject to certain adjustments, 70,840 shares of Quanta common stock valued at $1.5 million as of the settlement date of the applicable acquisition, and contingent consideration payments of up to $39.5 million , payable if financial targets are achieved by certain of the acquired businesses. Based on the estimated fair value of this contingent consideration, Quanta recorded a total of $18.7 million in liabilities as of the applicable dates of acquisition. The results of the acquired businesses have been included in Quanta’s consolidated financial statements since the respective dates of acquisition.

Quanta is in the process of finalizing its assessments of the fair values of the acquired assets and assumed liabilities related to businesses acquired subsequent to September 30, 2016 , and further adjustments to the purchase price allocations may occur. As of September 30, 2017 , the estimated fair values of the net assets acquired and the estimated contingent consideration liabilities were preliminary, with possible updates primarily related to certain tax estimates, property and equipment, other intangible assets and the fair value of contingent consideration. The aggregate purchase consideration of the businesses acquired subsequent to September 30, 2016 through September 30, 2017 was preliminarily allocated to acquired assets and assumed liabilities, which resulted in a preliminary allocation of $97.4 million to net tangible assets, $103.8 million to identifiable intangible assets and $311.4 million to goodwill.

The following table summarizes the aggregate consideration paid or payable as of September 30, 2017 for the 2017 acquisitions and 2016 acquisitions and presents the allocation of these amounts to the net tangible and identifiable intangible assets based on their estimated fair values as of the respective acquisition dates, inclusive of any purchase price adjustments. This allocation requires a significant use of estimates and is based on information that was available to management at the time these consolidated financial statements were prepared (in thousands).

Goodwill represents the excess of the purchase price over the net amount of the fair values assigned to assets acquired and liabilities assumed. The 2017 and 2016 acquisitions strategically expanded Quanta’s Canadian, Australian and domestic electric power, oil and gas and communications service offerings, which Quanta believes contributes to the recognition of the goodwill. In connection with the 2017 acquisitions, as of the acquisition dates, goodwill of $5.9 million was recorded for the acquired businesses that were included within Quanta’s Electric Power Infrastructure Services Division, and goodwill of $305.5 million was recorded for Stronghold, which is included within Quanta’s Oil and Gas Infrastructure Services Division. In connection with the 2016 acquisitions, as of the acquisition dates and inclusive of purchase price adjustments, goodwill of $23.6 million was recorded for the acquired businesses included within Quanta’s Electric Power Infrastructure Services Division and goodwill of $20.3 million was recorded for the acquired business included within Quanta’s Oil and Gas Infrastructure Services Division. Goodwill of $311.4 million and $2.0 million related to the 2017 acquisitions and 2016 acquisitions is expected to be deductible for income tax purposes.

The unaudited supplemental pro forma results of operations have been provided for illustrative purposes only and do not purport to be indicative of the actual results that would have been achieved by the combined companies for the periods presented or that may be achieved by the combined companies in the future. Future results may vary significantly from the results reflected in the following pro forma financial information because of future events and transactions, as well as other factors (in thousands, except per share amounts):

The pro forma combined results of operations for the three and nine months ended September 30, 2017 and 2016 were prepared by adjusting the historical results of Quanta to include the historical results of the 2017 acquisitions as if they occurred January 1, 2016 and the historical results of the 2016 acquisitions as if they occurred January 1, 2015 . These pro forma combined historical results were adjusted for the following: a reduction of interest expense as a result of the repayment of outstanding indebtedness of the acquired businesses; a reduction of interest income or an increase in interest expense as a result of the cash consideration paid net of cash received; an increase in amortization expense due to the incremental intangible assets recorded; changes in depreciation expense within cost of services to adjust acquired property and equipment to the acquisition date fair value and to conform with Quanta’s accounting policies; an increase in the number of outstanding shares of Quanta common stock; and reclassifications to conform the acquired companies’ presentation to Quanta’s accounting policies. The pro forma results of operations do not include any adjustments to eliminate the impact of acquisition-related costs or any cost savings or other synergies that resulted or may result from the acquisitions. As noted above, the pro forma results of operations do not purport to be indicative of the actual results that would have been achieved by the combined company for the periods presented or that may be achieved by the combined company in the future.

Revenues of approximately $87.2 million and a loss from continuing operations before income taxes of approximately $6.4 million , which included $3.2 million of acquisition-related costs, were included in Quanta’s consolidated results of operations for the three months ended September 30, 2017 related to the 2017 acquisitions. Revenues of approximately $89.4 million and a loss from continuing operations before income taxes of approximately $8.2 million , which included $5.4 million of acquisition-related

Adjustments primarily represent changes in deferred tax liability estimates and would not have had a material impact on the consolidated financial statements in prior periods had these adjustments been booked at the respective acquisition dates.

Also, as described in Note 2, Quanta’s operating units are organized into one of Quanta’s two internal divisions, and accordingly the goodwill associated with the operating units has been aggregated on a divisional basis in the table above. These divisions are closely aligned with Quanta’s reportable segments, and operating units are assigned to a division based on the predominant type of work performed. From time to time, an operating unit may be reorganized between divisions if its predominant business evolves.

Quanta’s intangible assets subject to amortization and the remaining weighted average amortization periods related to such assets were as follows (in thousands except for weighted average amortization periods, which are in years):