The following risk factors may be important to understanding any statement in this Annual Report on Form 10-K or elsewhere. Our business, financial condition and operating results can be affected by a number of factors, whether currently known or unknown, including but not limited to those described below. Any one or more of such factors could directly or indirectly cause our actual results of operations and financial condition to vary materially from past or anticipated future results of operations and financial condition. Any of these factors, in whole or in part, could materially and adversely affect our business, financial condition, results of operations and stock price.

Our revenue is highly dependent on transaction volumes in the global travel industry, particularly air travel transaction volumes.

Our Travel Network and Airline and Hospitality Solutions revenue is largely tied to travel suppliers’ transaction volumes rather than to their unit pricing for an airplane ticket, hotel room or other travel products. This revenue is generally not contractually committed to recur annually under our agreements with our travel suppliers. As a result, our revenue is highly dependent on the global travel industry, particularly air travel from which we derive a substantial amount of our revenue, and directly correlates with global travel, tourism and transportation transaction volumes. Our revenue is therefore highly susceptible to declines in or disruptions to leisure and business travel that may be caused by factors entirely out of our control, and therefore may not recur if these declines or disruptions occur.

Various factors may cause temporary or sustained disruption to leisure and business travel. The impact these disruptions would have on our business depends on the magnitude and duration of such disruption. These factors include, among others:

Our success depends on maintaining the integrity of our systems and infrastructure, which may suffer from failures, capacity constraints, business interruptions and forces outside of our control.

We may be unable to maintain and improve the efficiency, reliability and integrity of our systems. Unexpected increases in the volume of our business could exceed system capacity, resulting in service interruptions, outages and delays. These constraints can also lead to the deterioration of our services or impair our ability to process transactions. We occasionally experience system interruptions that make certain of our systems unavailable including, but not limited to, our GDS and the services that our Airline and Hospitality Solutions business provides to airlines and hotels. System interruptions may prevent us from efficiently providing services to customers or other third parties, which could cause damage to our reputation and result in our losing customers and revenues or cause us to incur litigation and liabilities. Although we have contractually limited our liability for damages caused by outages of our GDS (other than damages caused by our gross negligence or willful misconduct), we cannot guarantee that we will not be subject to lawsuits or other claims for compensation from our customers in connection with such outages for which we may not be indemnified or compensated.

Our systems may also be susceptible to external damage or disruption. Much of the computer and communications hardware upon which we depend is located across multiple data center facilities in a single geographic region. Our systems could be damaged or disrupted by power, hardware, software or telecommunication failures, human errors, natural events including floods, hurricanes, fires, winter storms, earthquakes and tornadoes, terrorism, break-ins, hostilities, war or similar events. Computer viruses, malware, denial of service attacks, attacks on hardware vulnerabilities, physical or electronic break-ins, cybersecurity incidents or other security breaches, and similar disruptions affecting the Internet, telecommunication services or our systems could cause service interruptions or the loss of critical data, and could prevent us from providing timely services. See “-Security breaches could expose us to liability and damage our reputation and our business.” Failure to efficiently provide services to customers or other third parties could cause damage to our reputation and result in the loss of customers and revenues, significant recovery costs or litigation and liabilities. Moreover, such risks are likely to increase as we expand our business and as the tools and techniques involved become more sophisticated.

Although we have implemented measures intended to protect certain systems and critical data and provide comprehensive disaster recovery and contingency plans for certain customers that purchase this additional protection, these protections and plans are not in place for all systems. Furthermore, several of our existing critical backup systems are located in the same metropolitan area as our primary systems and we may not have sufficient disaster recovery tools or resources available, depending on the type or size of the disruption. Disasters affecting our facilities, systems or personnel might be expensive to remedy and could significantly diminish our reputation and our brands, and we may not have adequate insurance to cover such costs.

Customers and other end-users who rely on our software products and services, including our SaaS and hosted offerings, for applications that are integral to their businesses may have a greater sensitivity to product errors and security vulnerabilities than customers for software products generally. Additionally, security breaches that affect third parties upon which we rely, such as travel suppliers, may further expose us to negative publicity, possible liability or regulatory penalties. Events outside our control could cause interruptions in our IT systems, which could have a material adverse effect on our business operations and harm our reputation.

We rely on the availability and performance of information technology services provided by third parties, including DXC Technology ("DXC"), which manages a significant portion of our systems.

Our businesses are largely dependent on the computer data centers and network systems operated for us by DXC, and its third-party providers, including AT&T, which DXC began outsourcing certain network services to in the fourth quarter of 2017. We also rely on other developers and service providers to maintain and support our global telecommunications infrastructure, including to connect our computer data center and call centers to end-users.

Our success is dependent on our ability to maintain effective relationships with these third-party technology and service providers. Some of our agreements with third-party technology and service providers are terminable for cause on short notice and often provide limited recourse for service interruptions. For example, our agreement with DXC provides us with limited indemnification rights. We could face significant additional cost or business disruption if:

In addition, DXC was formed in April 2017 from the spin-off of HP Enterprises' Services segment business and merger with CSC. There could be uncertainty, delays or disruptions in DXC's services as a result of these transactions, which could result in additional costs or business disruptions for us.

Security breaches could expose us to liability and damage our reputation and our business.

We process, store, and transmit large amounts of data, including personally identifiable information ("PII") and payment card industry data ("PCI") of our customers, and it is critical to our business strategy that our facilities and infrastructure, including those provided by DXC (as defined below) or other vendors, remain secure and are perceived by the marketplace to be secure. Our infrastructure may be vulnerable to physical or electronic break-ins, computer viruses, or similar disruptive problems.

In addition, we, like most technology companies, are the target of cybercriminals who attempt to compromise our systems.  We are subject to and experience threats and intrusions that have to be identified and remediated to protect sensitive information along with our intellectual property and our overall business. To address these threats and intrusions, we have a team of experienced security experts and support from firms that specialize in data security and cybersecurity. We are periodically subject to these threats and intrusions, and sensitive or material information could be compromised as a result. The costs of any investigation of such incidents, as well as any remediation related to these incidents, may be material. As previously disclosed, we became aware of an incident involving unauthorized access to payment information contained in a subset of hotel reservations processed through the Sabre Hospitality Solutions SynXis Central Reservation system (the “HS Central Reservation System”). Our investigation was supported by third party experts, including a leading cybersecurity firm. Our investigation determined that an unauthorized party: obtained access to account credentials that permitted access to a subset of hotel reservations processed through the HS Central Reservation System; used the account credentials to view a credit card summary page on the HS Central Reservation System and access payment card information (although we use encryption, this credential had the right to see unencrypted card data); and first obtained access to payment card information and some other reservation information on August 10, 2016. The last access to payment card information was on March 9, 2017. The unauthorized party was able to access information for certain hotel reservations, including cardholder name; payment card number; card expiration date; and, for a subset of reservations, card security code. The unauthorized party was also able, in some cases, to access certain information such as guest name(s), email, phone number, address, and other information if provided to the HS Central Reservation System. Information such as Social Security, passport, or driver’s license number was not accessed. The investigation did not uncover forensic evidence that the unauthorized party removed any information from the system, but it is a possibility. We took successful measures to ensure this unauthorized access to the HS Central Reservation System was stopped and is no longer possible. There is no indication that any of our systems beyond the HS Central Reservation System, such as Sabre’s Airline Solutions and Travel Network platforms, were affected or accessed by the unauthorized party. We notified law enforcement and the payment card brands, who engaged a PCI forensic investigator to investigate this incident. We have notified customers and other companies that use or interact with, directly or indirectly, the HS Central Reservation System about the incident. We are also cooperating with various governmental authorities that are investigating this incident. Separately, in November 2017, Sabre Hospitality Solutions observed a pattern of activity that, after further investigation, led it to believe that an unauthorized party improperly obtained access to certain hotel user credentials for purposes of accessing the HS Central Reservation System. We deactivated the compromised accounts and notified law enforcement of this activity. We also notified the payment card brands, and at their request, we have engaged a PCI forensic investigator to investigate this incident. We have not found any evidence of a breach of the network security of the HS Central Reservation System, and we believe that the number of affected reservations represents only a fraction of 1% of the bookings in the HS Central Reservation System. The costs related to these incidents, including any associated penalties assessed by any governmental authority or payment card brand, as well as any other impacts or remediation related to them, may be material. See Note 15. Commitments and Contingencies , to our consolidated financial statements for a discussion of a lawsuit filed in connection with these incidents. As noted below, we maintain insurance that covers certain aspects of cyber risks, and we continue to work with our insurance carriers in these matters.

Any computer viruses, malware, denial of service attacks, attacks on hardware vulnerabilities, physical or electronic break-ins, cybersecurity incidents, such as the items described above, or other security breach or compromise of the information handled by us or our service providers may jeopardize the security or integrity of information in our computer systems and networks or those of our customers and cause significant interruptions in our and our customers’ operations.

Any systems and processes that we have developed that are designed to protect customer information and prevent data loss and other security breaches cannot provide absolute security. In addition, we may not successfully implement remediation plans to address all potential exposures. It is possible that we may have to expend additional financial and other resources to address these problems. Failure to prevent or mitigate data loss or other security breaches could expose us or our customers to a risk of loss or misuse of such information, cause customers to lose confidence in our data protection measures, damage our reputation, adversely affect our operating results or result in litigation or potential liability for us. While we maintain insurance coverage that may, subject to policy terms and conditions, cover certain aspects of cyber risks, this insurance coverage is subject to a retention amount and may not be applicable to a particular incident or otherwise may be insufficient to cover all our losses beyond any retention. Similarly, we expect to continue to make significant investments in our information technology infrastructure. The implementation of these investments may be more costly or take longer than we anticipate, or could otherwise adversely affect our business operations, which could negatively impact our financial position, results of operations or cash flows.

Implementation of software solutions often involves a significant commitment of resources, and any failure to deliver as promised on a significant implementation could adversely affect our business.

In our Travel Network business and our Airline and Hospitality Solutions business, the implementation of software solutions often involves a significant commitment of resources and is subject to a number of significant risks over which we may or may not have control. These risks include:

As a result of these and other risks, some of our customers may incur large, unplanned costs in connection with the purchase and installation of our software products. Also, implementation projects could take longer than planned or fail. We may not be able to reduce or eliminate protracted installation or significant additional costs. Significant delays or unsuccessful customer implementation projects could result in cancellation or renegotiation of existing agreements, claims from customers, harm our reputation and negatively impact our operating results.

Our Travel Network business is exposed to pricing pressure from travel suppliers.

Travel suppliers continue to look for ways to decrease their costs and to increase their control over distribution. For example, consolidation in the airline industry, the growth of LCC/hybrids and macroeconomic factors, among other things, have driven some airlines to negotiate for lower fees during contract renegotiations, thereby exerting increased pricing pressure on our Travel Network business, which, in turn, negatively affects our revenues and margins. In addition, travel suppliers’ use of alternative distribution channels, such as direct distribution through supplier-operated websites, may also adversely affect our contract renegotiations with these suppliers and negatively impact our transaction fee revenue. For example, as we attempt to renegotiate new agreements with our travel suppliers, they may withhold some or all of their content (fares and associated economic terms) for distribution exclusively through their direct distribution channels (for example, the relevant airline’s website) or offer travelers more attractive terms for content available through those direct channels after their contracts expire. As a result of these sources of negotiating pressure, we may have to decrease our prices to retain their business. If we are unable to renew our contracts with these travel suppliers on similar economic terms or at all, or if our ability to provide this content is similarly impeded, this would also adversely affect the value of our Travel Network business as a marketplace due to our more limited content. See “—Travel suppliers’ use of alternative distribution models, such as direct distribution models, could adversely affect our Travel Network business.”

Our travel supplier customers may experience financial instability or consolidation, pursue cost reductions, change their distribution model or undergo other changes.

We generate the majority of our revenue and accounts receivable from airlines. We also derive revenue from hotels, car rental brands, rail carriers, cruise lines, tour operators and other suppliers in the travel and tourism industries. Adverse changes in any of these relationships or the inability to enter into new relationships could negatively impact the demand for and competitiveness of our travel products and services. For example, a lack of liquidity in the capital markets or weak economic performance may cause our travel suppliers to increase the time they take to pay or to default on their payment obligations, which could lead to a higher level of bad debt expense and negatively affect our results. Any large-scale bankruptcy or other insolvency proceeding of an airline or hospitality supplier could subject our agreements with that customer to rejection or early termination. Because we generally do not require security or collateral from our customers as a condition of sale, our revenues may be subject to credit risk more generally.

Furthermore, supplier consolidation, particularly in the airline industry, could harm our business. Our Travel Network business depends on a relatively small number of U.S.-based airlines for a substantial portion of its revenue, and all of our businesses are highly dependent on airline ticket volumes. Consolidation among airlines could result in the loss of an existing customer and the related fee revenue, decreased airline ticket volumes due to capacity restrictions implemented concurrently with the consolidation, and increased airline concentration and bargaining power to negotiate lower transaction fees. See "—Our Travel Network business is exposed to pricing pressure from travel suppliers." In addition, consolidation among travel suppliers may result in one or more suppliers refusing to provide certain content to Sabre but rather making it exclusively available on the suppliers’ proprietary websites, hurting the competitive position of our GDS relative to those websites. See “—Travel suppliers’ use of alternative distribution models, such as direct distribution models, could adversely affect our Travel Network business.”

Travel suppliers’ use of alternative distribution models, such as direct distribution models, could adversely affect our Travel Network business.

Some travel suppliers that provide content to Travel Network, including some of Travel Network’s largest airline customers, have sought to increase usage of direct distribution channels. For example, these travel suppliers are trying to move more consumer traffic to their proprietary websites, and some travel suppliers have explored direct connect initiatives linking their internal reservations systems directly with travel agencies or TMCs, thereby bypassing the GDSs. This direct distribution trend enables them to apply pricing pressure on intermediaries and negotiate travel distribution arrangements that are less favorable to intermediaries. With travel suppliers’ adoption of certain technology solutions over the last decade, including those offered by our Airline and Hospitality Solutions business, air travel suppliers have increased the proportion of direct bookings relative to indirect bookings. In the future, airlines may increase their use of direct distribution, which may cause a material decrease in their use of our GDS. Travel suppliers may also offer travelers advantages through their websites such as special fares and bonus miles, which could make their offerings more attractive than those available through our GDS platform. Similarly, travel suppliers may also seek to encourage travelers’ and travel agencies’ usage of their proprietary booking platforms by selectively increasing the ticket price in our GDS, making our GDS platform’s offerings more expensive than some alternative offerings. For example, we are currently engaged in litigation with the Lufthansa Group in connection with a surcharge that the Lufthansa Group has imposed on tickets purchased through three selected GDSs, including Sabre. The Lufthansa Group is seeking declaratory judgment that this surcharge does not violate the terms of its agreement with us, in addition to damages related to the allegations of breach of contract and tortious interference with agency contracts. We deny the allegations and we have filed a counterclaim that asserts the Lufthansa Group’s surcharge is a violation of its agreement and that seeks an order requiring the Lufthansa Group to specifically perform its obligations under the agreement.

In addition, with respect to ancillary products, travel suppliers may choose not to comply with the technical standards that would allow ancillary products to be immediately distributed via intermediaries, thus resulting in a delay before these products become available through our GDS relative to availability through direct distribution. In addition, if enough travel suppliers choose not to develop ancillary products in a standardized way with respect to technical standards our investment in adapting our various systems to enable the sale of ancillary products may not be successful.

Companies with close relationships with end consumers, like Facebook, as well as new entrants introducing new paradigms into the travel industry, such as metasearch engines, like Google, may promote alternative distribution channels to our GDS by diverting consumer traffic away from intermediaries, which may adversely affect our GDS business.

Additionally, technological advancements may allow airlines and hotels to facilitate broader connectivity to and integration with large travel buyers, such that certain airline and hotel offerings could be made available directly to such travel buyers without the involvement of intermediaries such as Travel Network and its competitors.

Any inability or failure to adapt to technological developments or the evolving competitive landscape could harm our business operations and competitiveness.

We depend upon the use of sophisticated information technology and systems. Our competitiveness and future results depend on our ability to maintain and make timely and cost-effective enhancements, upgrades and additions to our products, services, technologies and systems in response to new technological developments, industry standards and trends and customer demands. For example, IATA has promulgated its new distribution capability (“NDC”) standard. Depending on the level of adoption of this standard, our failure to integrate NDC into our technology or anticipate the evolution of next generation retailing and distribution could adversely affect our financial performance. As another example, migration of our enterprise applications and platforms to other hosting environments could cause us to incur substantial costs, as well as result in instability and business interruptions, which could materially harm our business.

Adapting to new technological and marketplace developments, such as NDC, may require substantial expenditures and lead time and we cannot guarantee that projected future increases in business volume will actually materialize. We may experience difficulties that could delay or prevent the successful development, marketing and implementation of enhancements, upgrades and additions. Moreover, we may fail to maintain, upgrade or introduce new products, services, technologies and systems as quickly as our competitors or in a cost-effective manner. For example, we must constantly update our GDS with new capabilities to adapt to the changing technological environment and customer needs. However, this process can be costly and time-consuming, and our efforts may not be successful as compared to our competitors in the travel distribution market. Those that we do develop may not achieve acceptance in the marketplace sufficient to generate material revenue or may be rendered obsolete or non-competitive by our competitors’ offerings.

In addition, our competitors are constantly increasing their product and service offerings through organic research and development or through strategic acquisitions. As a result, we must continue to invest significant resources in research and development in order to continually improve the speed, accuracy and comprehensiveness of our services and we may be required to make changes to our technology platforms or increase our investment in technology, increase marketing, adjust prices or business models and take other actions, which could affect our financial performance and liquidity.

Our ability to maintain and grow our Airline and Hospitality Solutions business may be negatively affected by competition from other third-party solutions providers and new participants that seek to enter the solutions market.

Our Airline and Hospitality Solutions business principally faces competition from existing third-party solutions providers. We also compete with various point solutions providers on a more limited basis in several discrete functional areas. For our Hospitality Solutions business, we face competition across many aspects of our business but our primary competitors are in the hospitality CRS and PMS fields.

Factors that may affect the competitive success of our Airline and Hospitality Solutions business include our pricing structure, our ability to keep pace with technological developments, the effectiveness and reliability of our implementation and system migration processes, our ability to meet a variety of customer specifications, the effectiveness and reliability of our systems, the cost and efficiency of our system upgrades and our customer support services. Our failure to compete effectively on these and other factors could decrease our market share, adversely impact our pricing or otherwise negatively affect our Airline and Hospitality Solutions business.

The travel distribution market is highly competitive, and we are subject to competition from other GDS providers, direct distribution by travel suppliers and new entrants or technologies that may challenge the GDS business model.

The evolution of the global travel and tourism industry, the introduction of new technologies and standards and the expansion of existing technologies in key markets, among other factors, could contribute to an intensification of competition in the business areas and regions in which we operate. Increased competition could require us to increase spending on marketing activities or product development, to decrease our booking or transaction fees and other charges (or defer planned increases in such fees and charges), to increase incentive consideration or take other actions that could harm our business. A GDS has two broad categories of customers: (i) travel suppliers, such as airlines, hotels, car rental brands, rail carriers, cruise lines and tour operators, and (ii) travel buyers, such as online and offline travel agencies, TMCs and corporate travel departments. The competitive positioning of a GDS depends on the success it achieves with both customer categories. Other factors that may affect the competitive success of a GDS include the comprehensiveness, timeliness and accuracy of the travel content offered, the reliability, ease of use and innovativeness of the technology, the perceived value proposition of our GDS by travel suppliers and travel buyers, the incentive consideration provided to travel agencies, the transaction fees charged to travel suppliers and the range of products and services available to travel suppliers and travel buyers. Our GDS competitors could seek to capture market share by offering more differentiated content, products or services, increasing the incentive consideration to travel agencies, or decreasing the transaction fees charged to travel suppliers, which would harm our business to the extent they gain market share from us or force us to respond by lowering our prices or increasing the incentive consideration we provide.

We cannot guarantee that we will be able to compete successfully against our current and future competitors in the travel distribution market, some of which may achieve greater brand recognition than us, have greater financial, marketing, personnel and other resources or be able to secure services and products from travel suppliers on more favorable terms. If we fail to overcome these competitive pressures, we may lose market share and our business may otherwise be negatively affected.

Our Travel Network business depends on relationships with travel buyers.

Our Travel Network business relies on relationships with several large travel buyers, including TMCs and OTAs, to generate a large portion of its revenue through bookings made by these travel companies. This revenue concentration in a relatively small number of travel buyers makes us particularly dependent on factors affecting those companies. For example, if demand for their services decreases, or if a key supplier pulls its content from us, travel buyers may stop utilizing our services or move all or some of their business to competitors or competing channels.

Although our contracts with larger travel agencies often increase the incentive consideration when the travel agency processes a certain volume or percentage of its bookings through our GDS, travel buyers are not contractually required to book exclusively through our GDS during the contract term. Travel buyers may shift bookings to other distribution intermediaries for many reasons, including to avoid becoming overly dependent on a single source of travel content or to increase their bargaining power with GDS providers. Additionally, some regulations allow travel buyers to terminate their contracts earlier.

These risks are exacerbated by increased consolidation among travel agencies and TMCs, which may ultimately reduce the pool of travel agencies that subscribe to GDSs. We must compete with other GDSs and other competitors for their business by offering competitive upfront incentive consideration, which, due to the strong bargaining power of these large travel buyers, tend to increase in each round of contract renewals. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Factors Affecting Our Results—Increasing travel agency incentive consideration" included in Part II, Item 7 for more information about our incentive consideration. However, any reduction in transaction fees from travel suppliers due to supplier consolidation or other market forces could limit our ability to increase incentive consideration to travel agencies in a cost-effective manner or otherwise affect our margins.

Our Travel Network business and our Airline and Hospitality Solutions business depend on maintaining and renewing contracts with their customers and other counterparties .

In our Travel Network business, we enter into participating carrier distribution and services agreements with airlines. Our contracts with major carriers typically last for three- to five-year terms and are generally subject to automatic renewal at the end of the term, unless terminated by either party with the required advance notice. Our contracts with smaller airlines generally last for one year and are also subject to automatic renewal at the end of the term, unless terminated by either party with the required advance notice. Airlines are not contractually obligated to distribute exclusively through our GDS during the contract term and may terminate their agreements with us upon providing the required advance notice after the expiration of the initial term. We cannot guarantee that we will be able to renew our airline contracts in the future on favorable economic terms or at all. See “—Our Travel Network business is exposed to pricing pressure from travel suppliers."

We also enter into contracts with travel buyers. Although most of our travel buyer contracts have terms of one to three years, we typically have non-exclusive, five- to ten-year contracts with our major travel agency customers. We also typically have three- to five-year contracts with corporate travel departments, which generally renew automatically unless terminated with the required advance notice. A meaningful portion of our travel buyer agreements, typically representing approximately 15% to 20% of our bookings, are up for renewal in any given year. We cannot guarantee that we will be able to renew our travel buyer agreements in the future on favorable economic terms or at all.

Similarly, our Airline and Hospitality Solutions business is based on contracts with travel suppliers for a typical duration of three to seven years for airlines and one to five years for hotels. We cannot guarantee that we will be able to renew our solutions contracts in the future on favorable economic terms or at all.

Additionally, we use several third-party distributor partners and joint ventures to extend our GDS services in EMEA and APAC. The termination of our contractual arrangements with any of these third-party distributor partners and joint ventures could adversely impact our Travel Network business in the relevant markets. See “—We rely on third-party distributor partners and joint ventures to extend our GDS services to certain regions, which exposes us to risks associated with lack of direct management control and potential conflicts of interest” for more information on our relationships with our third-party distributor partners and joint ventures.

Our failure to renew some or all of these agreements on economically favorable terms or at all, or the early termination of these existing contracts, would adversely affect the value of our Travel Network business as a marketplace due to our limited content and distribution reach, which could cause some of our subscribers to move to a competing GDS or use other travel technology providers for the solutions we provide and would materially harm our business, reputation and brand. Our business therefore relies on our ability to renew our agreements with our travel buyers, travel suppliers, third-party distributor partners and joint ventures or developing relationships with new travel buyers and travel suppliers to offset any customer losses.

We are subject to a certain degree of revenue concentration among a portion of our customer base. Because of this concentration among a small number of customers, if an event were to adversely affect one of these customers, it could have a material impact on our business.

Our ability to recruit, train and retain employees, including our key executive officers and technical employees, is critical to our results of operations and future growth.

Our continued ability to compete effectively depends on our ability to recruit new employees and retain and motivate existing employees, particularly professionals with experience in our industry, information technology and systems, as well as our key executive officers. For example, the specialized skills we require can be difficult and time-consuming to acquire and are often in short supply. There is high demand and competition for well-qualified employees on a global basis, such as software engineers, developers and other technology professionals with specialized knowledge in software development, especially expertise in certain programming languages. This competition affects both our ability to retain key employees and to hire new ones. Similarly, uncertainty in the global political environment may adversely affect our ability to hire and retain key employees.

Any of our employees may choose to terminate their employment with us at any time, and a lengthy period of time is required to hire and train replacement employees when such skilled individuals leave the company. For example, Sean Menke was elected as President and Chief Executive Officer of Sabre on December 31, 2016. Subsequent to his election, we have announced modifications to our business strategies and increased long-term investment in key areas, such as technology infrastructure, that may continue to have a negative impact in the short term due to expected increases in operating expenses and capital expenditures.

If we fail to attract well-qualified employees or to retain or motivate existing employees, our business could be materially hindered by, for example, a delay in our ability to deliver products and services under contract, bring new products and services to market or respond swiftly to customer demands or new offerings from competitors. Even if we are able to maintain our employee base, the resources needed to recruit and retain such employees may adversely affect our business, financial condition and results of operations.

Our collection, processing, storage, use and transmission of personal data could give rise to liabilities as a result of governmental regulation, conflicting legal requirements, differing views on data privacy or security breaches.

We collect, process, store, use and transmit a large volume of personal data on a daily basis, including, for example, to process travel transactions for our customers and to deliver other travel-related products and services. Personal data is increasingly subject to legal and regulatory protections around the world, which vary widely in approach and which possibly conflict with one another. In recent years, for example, U.S. legislators and regulatory agencies, such as the Federal Trade Commission, as well as U.S. states, have increased their focus on protecting personal data by law and regulation, and have increased enforcement actions for violations of privacy and data protection requirements. The European Commission also recently approved and adopted the GDPR, a new data protection law, which will apply beginning in May 2018. These data protection laws and regulations are intended to protect the privacy and security of personal data, including credit card information that is collected, processed and transmitted in or from the relevant jurisdiction. Implementation of and compliance with these laws and regulations may be more costly or take longer than we anticipate, or could otherwise adversely affect our business operations, which could negatively impact our financial position or cash flows. Additionally, media coverage of data breaches has escalated, in part because of the increased number of enforcement actions, investigations and lawsuits. As this focus and attention on privacy and data protection increases, we also risk exposure to potential liabilities and costs resulting from the compliance with, or any failure to comply with applicable legal requirements, conflicts among these legal requirements or differences in approaches to privacy and security of travel data. Our business could be materially adversely affected by our inability, or the inability of our vendors who receive personal data from us, to comply with legal obligations regarding the use of personal data, new data handling requirements that conflict with or negatively impact our business practices. In addition, our agreements with customers may also require that we indemnify the customer for liability arising from data breaches under the terms of our agreements with these customers. These indemnification obligations could be significant and may exceed the limits of any applicable insurance policy we maintain. See “—Security breaches could expose us to liability and damage our reputation and our business.”

We are exposed to risks associated with PCI compliance.

The PCI Data Security Standard (“PCI DSS”) is a specific set of comprehensive security standards required by credit card brands for enhancing payment account data security, including but not limited to requirements for security management, policies, procedures, network architecture, and software design. PCI DSS compliance is required in order to maintain credit card processing services. The cost of compliance with PCI DSS is significant and may increase as the requirements change. We are tested periodically for assurance and successfully completed our last annual assessment in September 2017. Compliance does not guarantee a completely secure environment and notwithstanding the results of this assessment there can be no assurance that payment card brands will not request further compliance assessments or set forth additional requirements to maintain access to credit card processing services. See “-Security breaches could expose us to liability and damage our reputation and our business.” Compliance is an ongoing effort and the requirements evolve as new threats are identified. In the event that we were to lose PCI DSS compliance status (or fail to renew compliance under a future version of the PCI DSS), we could be exposed to increased operating costs, fines and penalties and, in extreme circumstances, may have our credit card processing privileges revoked, which would have a material adverse effect on our business.

Our business could be harmed by adverse global and regional economic and political conditions.

Travel expenditures are sensitive to personal and business discretionary spending levels and grow more slowly or decline during economic downturns. We derive the majority of our revenue from the United States and Europe, and we have expanded Travel Network's presence in APAC. Our geographic concentration in the United States and Europe, as well as our expanded focus in APAC, makes our business potentially vulnerable to economic and political conditions that adversely affect business and leisure travel originating in or traveling to these regions.

Despite modest growth in the U.S. economy, there is still weakness in other parts of the global economy, including increased unemployment, reduced financial capacity of both business and leisure travelers, diminished liquidity and credit availability, declines in consumer confidence and discretionary income and general uncertainty about economic stability. Furthermore, recent changes in the U.S. political environment have resulted in additional uncertainties with respect to travel restrictions, and the regulatory, tax and economic environment in the United States, which could adversely impact travel demand, our business operations or our financial results. We cannot predict the magnitude, length or recurrence of recessionary or low-growth economic patterns, which have impacted, and may continue to impact, demand for travel and lead to reduced spending on the services we provide.

We derive the remainder of our revenues from Latin America, the Middle East and Africa and APAC. Any unfavorable economic, political or regulatory developments in these regions could negatively affect our business, such as delays in payment or non-payment of contracts, delays in contract implementation or signing, carrier control issues and increased costs from regulatory changes particularly as parts of our growth strategy involve expanding our presence in these emerging markets. For example, markets that have traditionally had a high level of exports to China, or that have commodities-based economies, have continued to experience slowing or deteriorating economic conditions. These adverse economic conditions may negatively impact our business results in those regions.

Similarly, in Venezuela, due to currency controls that impact the ability of certain of our airline customers operating in the country to obtain U.S. dollars to make timely payments to us, the collection of accounts receivable due to us can be, and has been, delayed. Due to the nature of this delay, we are deferring the recognition of any future revenues until cash is collected in accordance with our policies. Accordingly, our accounts receivable are subject to a general collection risk, as there can be no assurance that we will be paid from such customers in a timely manner, if at all. In response to the political and economic uncertainty in Venezuela, certain airlines have scaled back operations in response to the reduced demand for travel by local consumers as well as the currency controls which has impacted our airline customers in Venezuela.

Voters in the U.K. have approved the exit of that country from the E.U. (“Brexit”), and the British government has provided official notification to the E.U. that it intends to withdraw from the E.U. The Brexit vote and related process have created significant economic uncertainty in the U.K. and in EMEA, which may negatively impact our business results in those regions. In addition, the terms of the U.K.’s withdrawal from the E.U., once negotiated, could potentially disrupt the markets we serve and the tax jurisdictions in which we operate and adversely change tax benefits or liabilities in these or other jurisdictions, and may cause us to lose customers, suppliers, and employees. In addition, Brexit could lead to legal uncertainty and potentially divergent national laws and regulations as the U.K. determines which E.U. laws to replace or replicate.

We operate a global business that exposes us to risks associated with international activities.

Our international operations involve risks that are not generally encountered when doing business in the United States. These risks include, but are not limited to:

Any of the foregoing risks may adversely affect our ability to conduct and grow our business internationally.

We rely on the value of our brands, which may be damaged by a number of factors, some of which are out of our control.

We believe that maintaining and expanding our portfolio of product and service brands are important aspects of our efforts to attract and expand our customer base. Our brands may be negatively impacted by, among other things, unreliable service levels from third-party providers, customers’ inability to properly interface their applications with our technology, the loss or unauthorized disclosure of personal data, including PCI or PII, or other bad publicity due to litigation, regulatory concerns or otherwise relating to our business. See “—Security breaches could expose us to liability and damage our reputation and our business.” Any inability to maintain or enhance awareness of our brands among our existing and target customers could negatively affect our current and future business prospects.

We are involved in various legal proceedings which may cause us to incur significant fees, costs and expenses and may result in unfavorable outcomes.

We are involved in various legal proceedings that involve claims for substantial amounts of money or which involve how we conduct our business. See Note 15. Commitments and Contingencies , to our consolidated financial statements. For example, the court has entered a judgment against us as a result of the jury verdict we recently received in the antitrust litigation with US Airways, and we have appealed this judgment. Other parties might likewise seek to benefit from any unfavorable outcome by threatening to bring or actually bringing their own claims against us on the same or similar grounds or utilizing the litigation to seek more favorable contract terms. We are also subject to a U.S. Department of Justice ("DOJ") antitrust investigation from 2011 relating to the pricing and conduct of the airline distribution industry. We received a civil investigation demand ("CID") from the DOJ and we are fully cooperating. The DOJ has also sent CIDs to other companies in the travel industry. Based on its findings in the investigation, the DOJ may (i) close the file, (ii) seek a consent decree to remedy issues it believes violate the antitrust laws, or (iii) file suit against us for violating the antitrust laws, seeking injunctive relief. Depending on the outcome of any of these proceedings, and the scope of the outcome, the manner in which our airline distribution business is operated could be affected and could potentially force changes to the existing airline distribution business model.

The defense of these actions, as well as any of the other actions described under Note 15. Commitments and Contingencies , to our consolidated financial statements or elsewhere in this Annual Report on Form 10-K, and any other actions brought against us in the future, is time consuming and diverts management’s attention. Even if we are ultimately successful in defending ourselves in such matters, we are likely to incur significant fees, costs and expenses as long as they are ongoing. Any of these consequences could have a material adverse effect on our business, financial condition and results of operations.

Any failure to comply with regulations or any changes in such regulations governing our businesses could adversely affect us.

Parts of our business operate in regulated industries and could be adversely affected by unfavorable changes in or the enactment of new laws, rules or regulations applicable to us, which could decrease demand for our products and services, increase costs or subject us to additional liabilities. Moreover, regulatory authorities have relatively broad discretion to grant, renew and revoke licenses and approvals and to implement or interpret regulations. Accordingly, these regulatory authorities could prevent or temporarily suspend us from carrying on some or all of our activities or otherwise penalize us if our practices were found not to comply with the applicable regulatory or licensing requirements or any interpretation of such requirements by the regulatory authority. Our failure to comply with any of these requirements or interpretations could have a material adverse effect on our operations.

Further, the United States has imposed economic sanctions that affect transactions with designated countries, including Cuba, Iran, Crimea region, North Korea and Syria, and nationals and others of those countries, and certain specifically targeted individuals and entities engaged in conduct detrimental to U.S. national security interests. These sanctions are administered by the OFAC and are typically known as the OFAC regulations. These regulations are extensive and complex, and they differ from one sanctions regime to another. Failure to comply with these regulations could subject us to legal and reputational consequences, including civil and criminal penalties.

We have GDS contracts with carriers that fly to Cuba, Iran, Crimea region, North Korea and Syria but are based outside of those countries and are not owned by those governments or nationals of those governments. With respect to Iran, Sudan, North Korea and Syria we believe that our activities are designed to comply with certain information and travel-related exemptions. With respect to Cuba, we have advised OFAC that customers outside the United States we display on the Sabre GDS flight information for, and support booking and ticketing of, services of non-Cuban airlines that offer service to Cuba. Based on advice of counsel, we believe these activities to fall under an exemption from OFAC regulations applicable to the transmission of information and informational materials and transactions related thereto.

We believe that our activities with respect to these countries are known to OFAC. We note, however, that OFAC regulations and related interpretive guidance are complex and subject to varying interpretations. Due to this complexity, OFAC’s interpretation of its own regulations and guidance vary on a case to case basis. As a result, we cannot provide any guarantees that OFAC will not challenge any of our activities in the future, which could have a material adverse effect on our results of operations.

In Europe, GDS regulations or interpretations thereof may increase our cost of doing business or lower our revenues, limit our ability to sell marketing data, impact relationships with travel buyers, airlines, rail carriers or others, impair the enforceability of existing agreements with travel buyers and other users of our system, prohibit or limit us from offering services or products, or limit our ability to establish or change fees. Although regulations specifically governing GDSs have been lifted in the United States, they remain subject to general regulation regarding unfair trade practices by the U.S. Department of Transportation (“DOT”). In addition, continued regulation of GDSs in the E.U. and elsewhere could also create the operational challenge of supporting different products, services and business practices to conform to the different regulatory regimes. We do not currently maintain a central database of all regulatory requirements affecting our worldwide operations and, as a result, the risk of non-compliance with the laws and regulations described above is heightened. Our failure to comply with these laws and regulations may subject us to fines, penalties and potential criminal violations. Any changes to these laws or regulations or any new laws or regulations may make it more difficult for us to operate our business.

We rely on third-party distributor partners and joint ventures to extend our GDS services to certain regions, which exposes us to risks associated with lack of direct management control and potential conflicts of interest.

Our Travel Network business utilizes third-party distributor partners and joint ventures to extend our GDS services in EMEA and APAC. We work with these partners to establish and maintain commercial and customer service relationships with both travel suppliers and travel buyers. Since, in many cases, we do not exercise full management control over their day-to-day operations, the success of their marketing efforts and the quality of the services they provide are beyond our control. If these partners do not meet our standards for distribution, our reputation may suffer materially, and sales in those regions could decline significantly. Any interruption in these third-party services, deterioration in their performance or termination of our contractual arrangements with them could negatively impact our ability to extend our GDS services in the relevant markets. In addition, our business may be harmed due to potential conflicts of interest with our joint venture partners.

We use open source software in our solutions that may subject our software solutions to general release or require us to re-engineer our solutions.

We use open source software in our solutions and may use more open source software in the future. From time to time, there have been claims by companies claiming ownership of software that was previously thought to be open source and that was incorporated by other companies into their products. As a result, we could be subject to suits by parties claiming ownership of what we believe to be open source software. Some open source licenses contain requirements that we make available source code for modifications or derivative works we create based upon the open source software and that we license these modifications or derivative works under the terms of a particular open source license or other license granting third parties certain rights of further use. If we combine or, in some cases, link our proprietary software solutions with or to open source software in a certain manner, we could, under certain of the open source licenses, be required to release the source code of our proprietary software solutions or license such proprietary solutions under the terms of a particular open source license or other license granting third parties certain rights of further use. In addition to risks related to license requirements, usage of open source software can lead to greater risks than use of third-party commercial software, as open source licensors generally do not provide warranties or controls on origin of the software. In addition, open source license terms may be ambiguous and many of the risks associated with usage of open source cannot be eliminated, and could, if not properly addressed, negatively affect our business. If we were found to have inappropriately used open source software, we may be required to seek licenses from third parties in order to continue offering our software, to re-engineer our solutions, to discontinue the sale of our solutions in the event re-engineering cannot be accomplished on a timely basis or take other remedial action that may divert resources away from our development efforts, any of which could adversely affect our business, operating results and financial condition.

We are exposed to risks associated with acquiring or divesting businesses or business operations.

We have acquired, and, as part of our growth strategy, may in the future acquire, businesses or business operations. We may not be able to identify suitable candidates for additional business combinations and strategic investments, obtain financing on acceptable terms for such transactions, obtain necessary regulatory approvals or otherwise consummate such transactions on acceptable terms, or at all. Any acquisitions that we are able to identify and complete may also involve a number of risks, including our inability to successfully or profitably integrate, operate, maintain and manage our newly acquired operations or employees; the diversion of our management’s attention from our existing business to integrate operations and personnel; possible material adverse effects on our results of operations during the integration process; becoming subject to contingent or other liabilities, including liabilities arising from events or conduct predating the acquisition that were not known to us at the time of the acquisition; and our possible inability to achieve the intended objectives of the transaction, including the inability to achieve cost savings and synergies. Acquisitions may also have unanticipated tax, regulatory and accounting ramifications, including recording goodwill and nonamortizable intangible assets that are subject to impairment testing on a regular basis and potential periodic impairment charges and incurring amortization expenses related to certain intangible assets. To consummate any such transactions, we may need to raise external funds through the sale of equity or the issuance of debt in the capital markets or through private placements, which may affect our liquidity and may dilute the value of our common stock. See "—We have a significant amount of indebtedness, which could adversely affect our cash flow and our ability to operate our business and to fulfill our obligations under our indebtedness."

We have also divested, and may in the future divest, businesses or business operations. Any divestitures may involve a number of risks, including the diversion of management’s attention, significant costs and expenses, the loss of customer relationships and cash flow, and the disruption of the affected business or business operations. Failure to timely complete or to consummate a divestiture may negatively affect the valuation of the affected business or business operations or result in restructuring charges.

Intellectual property infringement actions against us could be costly and time consuming to defend and may result in business harm if we are unsuccessful in our defense.

Third parties may assert, including by means of counterclaims against us as a result of the assertion of our intellectual property rights, that our products, services or technology, or the operation of our business, violate their intellectual property rights. We are currently subject to such assertions, including patent infringement claims, and may be subject to such assertions in the future. These assertions may also be made against our customers who may seek indemnification from us. In the ordinary course of business, we enter into agreements that contain indemnity obligations whereby we are required to indemnify our customers against these assertions arising from our customers’ usage of our products, services or technology. As the competition in our industry increases and the functionality of technology offerings further overlaps, these claims and counterclaims could become more common. We cannot be certain that we do not or will not infringe third parties’ intellectual property rights.

Legal proceedings involving intellectual property rights are highly uncertain, and can involve complex legal and scientific questions. Any intellectual property claim against us, regardless of its merit, could result in significant liabilities to our business, and can be expensive and time consuming to defend. Depending on the nature of such claims, our businesses may be disrupted, our management’s attention and other company resources may be diverted and we may be required to redesign, reengineer or rebrand our products and services, if feasible, to stop offering certain products and services or to enter into royalty or licensing agreements in order to obtain the rights to use necessary technologies, which may not be available on terms acceptable to us, if at all, and may result in a decrease of our competitive advantage. Our failure to prevail in such matters could result in loss of intellectual property rights, judgments awarding substantial damages, including possible treble damages and attorneys’ fees, and injunctive or other equitable relief against us. If we are held liable, we may be unable to exploit some or all of our intellectual property rights or technology. Even if we are not held liable, we may choose to settle claims by making a monetary payment or by granting a license to intellectual property rights that we otherwise would not license. Further, judgments may result in loss of reputation, may force us to take costly remediation actions, delay selling our products and offering our services, reduce features or functionality in our services or products, or cease such activities altogether. Insurance may not cover or be insufficient for any such claim.

We may not have sufficient insurance to cover our liability in pending litigation claims and future claims either due to coverage limits or as a result of insurance carriers seeking to deny coverage of such claims, which in either case could expose us to significant liabilities.

We maintain third-party insurance coverage against various liability risks, including securities, stockholders, derivative, ERISA, and product liability claims, as well as other claims that form the basis of litigation matters pending against us. We believe these insurance programs are an effective way to protect our assets against liability risks. However, the potential liabilities associated with litigation matters pending against us, or that could arise in the future, could exceed the coverage provided by such programs. In addition, our insurance carriers have in the past sought or may in the future seek to rescind or deny coverage with respect to pending claims or lawsuits, completed investigations or pending or future investigations and other legal actions against us. If we do not have sufficient coverage under our policies, or if the insurance companies are successful in rescinding or denying coverage, we may be required to make material payments in connection with third-party claims.

We may not be able to protect our intellectual property effectively, which may allow competitors to duplicate our products and services.

Our success and competitiveness depend, in part, upon our technologies and other intellectual property, including our brands. Among our significant assets are our proprietary and licensed software and other proprietary information and intellectual property rights. We rely on a combination of copyright, trademark and patent laws, laws protecting trade secrets, confidentiality procedures and contractual provisions to protect these assets both in the United States and in foreign countries. The laws of some jurisdictions may provide less protection for our technologies and other intellectual property assets than the laws of the United States.

There is no certainty that our intellectual property rights will provide us with substantial protection or commercial benefit. Despite our efforts to protect our intellectual property, some of our innovations may not be protectable, and our intellectual property rights may offer insufficient protection from competition or unauthorized use, lapse or expire, be challenged, narrowed, invalidated, or misappropriated by third parties, or be deemed unenforceable or abandoned, which could have a material adverse effect on our business, financial condition and results of operations and the legal remedies available to us may not adequately compensate us. We cannot be certain that others will not independently develop, design around, or otherwise acquire equivalent or superior technology or intellectual property rights.

We license software and other intellectual property from third parties. These licensors may breach or otherwise fail to perform their obligations, or claim that we have breached or otherwise attempt to terminate their license agreements with us. We also rely on license agreements to allow third parties to use our intellectual property rights, including our software, but there is no guarantee that our licensees will abide by the terms of our license agreements or that the terms of our agreements will always be enforceable.

In addition, policing unauthorized use of and enforcing intellectual property can be difficult and expensive. The fact that we have intellectual property rights, including registered intellectual property rights, may not guarantee success in our attempts to enforce these rights against third parties. Besides general litigation risks, changes in, or interpretations of, intellectual property laws may compromise our ability to enforce our rights. We may not be aware of infringement or misappropriation, or elect not to seek to prevent it. Our decisions may be based on a variety of factors, such as costs and benefits of taking action, and contextual business, legal, and other issues. Any inability to adequately protect our intellectual property on a cost-effective basis could harm our business.

Defects in our products may subject us to significant warranty liabilities or product liability claims and we may have insufficient product liability insurance to pay material uninsured claims.

Our business exposes us to the risk of product liability claims that are inherent in software development. We may inadvertently create defective software, or supply our customers with defective software or software components that we acquire from third parties, which could result in personal injury, property damage or other liabilities, and may result in warranty or product liability claims brought against us, our travel supplier customers or third parties.

Under our customer agreements, we generally must indemnify our customers for liability arising from intellectual property infringement claims with respect to our software. These indemnification obligations could be significant and we may not have adequate insurance coverage to protect us against all claims. The combination of our insurance coverage, cash flows and reserves may not be adequate to satisfy product liabilities we may incur in the future. Even meritless claims could subject us to adverse publicity, hinder us from securing insurance coverage in the future, require us to incur significant legal fees, decrease demand for any products that we successfully develop, divert management’s attention, and force us to limit or forgo further development and commercialization of these products. The cost of any product liability litigation or other proceedings, even if resolved in our favor, could be substantial.

We may have higher than anticipated tax liabilities.

We are subject to a variety of taxes in many jurisdictions globally, including income taxes in the United States at the federal, state and local levels, and in many other countries. Significant judgment is required in determining our worldwide provision for income taxes. In the ordinary course of our business, there are many transactions and calculations where the ultimate tax determination is uncertain. We operate in numerous countries where our income tax returns are subject to audit and adjustment by local tax authorities. Because we operate globally, the nature of the uncertain tax positions is often very complex and subject to change, and the amounts at issue can be substantial. It is inherently difficult and subjective to estimate such amounts, as we have to determine the probability of various possible outcomes. We re-evaluate uncertain tax positions on a quarterly basis. This evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit and new audit activity. Although we believe our tax estimates are reasonable, the final determination of tax audits could be materially different from our historical income tax provisions and accruals. Our effective tax rate may change from year to year based on changes in the mix of activities and income allocated or earned among various jurisdictions, tax laws in these jurisdictions, tax treaties between countries, our eligibility for benefits under those tax treaties, and the estimated values of deferred tax assets and liabilities. Such changes could result in an increase in the effective tax rate applicable to all or a portion of our income which would reduce our profitability.

We establish reserves for our potential liability for U.S. and non-U.S. taxes, including sales, occupancy and value-added taxes (“VAT”), consistent with applicable accounting principles and in light of all current facts and circumstances. We also establish reserves when required relating to the collection of refunds related to value-added taxes, which are subject to audit and collection risks in various countries. Historically our right to recover certain value-added tax receivables associated with our European businesses has been questioned by tax authorities. These reserves represent our best estimate of our contingent liability for taxes. The interpretation of tax laws and the determination of any potential liability under those laws are complex, and the amount of our liability may exceed our established reserves.

We consider the investment in our foreign subsidiaries as of December 31, 2017 to be indefinitely reinvested and, accordingly, no U.S. income taxes have been provided thereon.

New tax laws, statutes, rules, regulations or ordinances could be enacted at any time and existing tax laws, statutes, rules, regulations and ordinances could be interpreted, changed, modified or applied adversely to us. These events could require us to pay additional tax amounts on a prospective or retroactive basis, as well as require us to pay fees, penalties or interest for past amounts deemed to be due. New, changed, modified or newly interpreted or applied laws could also increase our compliance, operating and other costs, as well as the costs of our products and services. For example, on December 22, 2017, the Tax Cuts and Jobs Act (the “TCJA”) was signed into law. The TCJA contains significant changes to the U.S. corporate income tax system, including a reduction of the federal corporate income tax rate from 35% to 21%, a limitation of the tax deduction for interest expense to 30% of adjusted taxable income (as defined in the TCJA), base erosion provisions related to intercompany foreign payments and global low-taxed income, one-time taxation of offshore earnings at reduced rates in connection with the transition of U.S. international taxation from a worldwide tax system to a territorial tax system, elimination of U.S. tax on foreign earnings (subject to certain important exceptions), and modifying or repealing many business deductions and credits. We continue to evaluate the potential effects that the TCJA may have on our operations, cash flows and results of operations. Notwithstanding the reduction in the federal corporate income tax rate, the future impact of the TCJA, including on our global operations, is uncertain, and our business and financial condition could be adversely affected. 

We may recognize impairments on long-lived assets, including goodwill and other intangible assets, or recognize impairments on our equity method investments.

Our consolidated balance sheet at December 31, 2017 contained goodwill and intangible assets, net totaling $3.2 billion . Future acquisitions that result in the recognition of additional goodwill and intangible assets would cause an increase in these types of assets. We do not amortize goodwill and intangible assets that are determined to have indefinite useful lives, but we amortize definite-lived intangible assets on a straight-line basis over their useful economic lives, which range from four to thirty years, depending on classification.

We evaluate goodwill for impairment on an annual basis or earlier if impairment indicators exist and we evaluate definite-lived intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of definite-lived intangible assets used in combination to generate cash flows largely independent of other assets may not be recoverable. We record an impairment charge whenever the estimated fair value of our reporting units or of such intangible assets is less than its carrying value.

The fair values used in our impairment evaluation are estimated using a combined approach based upon discounted future cash flow projections and observed market multiples for comparable businesses. Changes in estimates based on changes in risk-adjusted discount rates, future booking and transaction volume levels, future price levels, rates of growth in our consumer and corporate direct booking businesses, rates of increase in operating expenses, cost of revenue and taxes could result in material impairment charges.

Our pension plan obligations are currently unfunded, and we may have to make significant cash contributions to our plans, which could reduce the cash available for our business.

Our pension plans in the aggregate are estimated to be unfunded by $112 million as of December 31, 2017. With approximately 5,000 participants in our pension plans, we incur substantial costs relating to pension benefits, which can vary substantially as a result of changes in healthcare laws and costs, volatility in investment returns on pension plan assets and changes in discount rates used to calculate related liabilities. Our estimates of liabilities and expenses for pensions and other post-retirement healthcare benefits require the use of assumptions, including assumptions relating to the rate used to discount the future estimated liability, the rate of return on plan assets, inflation and several assumptions relating to the employee workforce (medical costs, retirement age and mortality). Actual results may differ, which may have a material adverse effect on our business, prospects, financial condition or results of operations. Future volatility and disruption in the stock markets could cause a decline in the asset values of our pension plans. In addition, a decrease in the discount rate used to determine minimum funding requirements could result in increased future contributions. If either occurs, we may need to make additional pension contributions above what is currently estimated, which could reduce the cash available for our businesses.

We may require more cash than we generate in our operating activities, and additional funding on reasonable terms or at all may not be available.

We cannot guarantee that our business will generate sufficient cash flow from operations to fund our capital investment requirements or other liquidity needs. Moreover, because we are a holding company with no material direct operations, we depend on loans, dividends and other payments from our subsidiaries to generate the funds necessary to meet our financial obligations. Our subsidiaries are legally distinct from us and may be prohibited or restricted from paying dividends or otherwise making funds available to us under certain conditions.

As a result, we may be required to finance our cash needs through bank loans, additional debt financing, public or private equity offerings or otherwise. Our ability to arrange financing and the cost of such financing are dependent on numerous factors, including but not limited to general economic and capital market conditions, the availability of credit from banks or other lenders, investor confidence in us, and our results of operations.

There can be no assurance that financing will be available on terms favorable to us or at all, which could force us to delay, reduce or abandon our growth strategy, increase our financing costs, or both. Additional funding from debt financings may make it more difficult for us to operate our business because a portion of our cash generated from internal operations would be used to make principal and interest payments on the indebtedness and we may be obligated to abide by restrictive covenants contained in the debt financing agreements, which may, among other things, limit our ability to make business decisions and further limit our ability to pay dividends.

In addition, any downgrade of our debt ratings by Standard & Poor’s, Moody’s Investor Service or similar ratings agencies, increases in general interest rate levels and credit spreads or overall weakening in the credit markets could increase our cost of capital. Furthermore, raising capital through public or private sales of equity to finance acquisitions or expansion could cause earnings or ownership dilution to your shareholding interests in our company.

We have a significant amount of indebtedness, which could adversely affect our cash flow and our ability to operate our business and to fulfill our obligations under our indebtedness.

We have a significant amount of indebtedness. As of December 31, 2017, we had $3.5 billion of indebtedness outstanding in addition to $379 million of availability under our Revolver, after taking into account the availability reduction of $21 million for letters of credit issued under our Revolver. Our substantial level of indebtedness increases the possibility that we may not generate enough cash flow from operations to pay, when due, the principal of, interest on or other amounts due in respect of, these obligations. Other risks relating to our long-term indebtedness include:

In addition, it is possible that we may need to incur additional indebtedness in the future in the ordinary course of business. The terms of our Amended and Restated Credit Agreement and the indentures governing our senior secured notes due in 2023 allow us to incur additional debt subject to certain limitations. If new debt is added to current debt levels, the risks described above could intensify. In addition, our inability to maintain certain leverage ratios could result in acceleration of a portion of our debt obligations and could cause us to be in default if we are unable to repay the accelerated obligations.

We are exposed to interest rate fluctuations.

Our floating rate indebtedness exposes us to fluctuations in prevailing interest rates. To reduce the impact of large fluctuations in interest rates, we typically hedge a portion of our interest rate risk by entering into derivative agreements with financial institutions. Our exposure to interest rates relates primarily to our borrowings under the Amended and Restated Credit Agreement.

The derivative agreements that we use to manage the risk associated with fluctuations in interest rates may not be able to eliminate the exposure to these changes. Interest rates are sensitive to numerous factors outside of our control, such as government and central bank monetary policy in the jurisdictions in which we operate. Depending on the size of the exposures and the relative movements of interest rates, if we choose not to hedge or fail to effectively hedge our exposure, we could experience a material adverse effect on our results of operations and financial condition.

We are exposed to exchange rate fluctuations.

We conduct various operations outside the United States, primarily in APAC, Europe and Latin America. During the year ended December 31, 2017, foreign currency operations included $256 million of revenue and $595 million of operating expenses, representing approximately 7% and 20% of our total revenue and operating expenses, respectively. During the year ended December 31, 2016, foreign currency operations included $211 million of revenue and $666 million of operating expenses, representing approximately 6% and 23% of our total revenue and operating expenses, respectively. Our most significant foreign currency operating expenses are in the Euro, representing approximately 8% and 7% of our operating expenses for the year ended December 31, 2017 and 2016, respectively. As a result, we face exposure to movements in currency exchange rates. These exposures include but are not limited to:

Depending on the size of the exposures and the relative movements of exchange rates, if we choose not to hedge or fail to hedge effectively our exposure, we could experience a material adverse effect on our results of operations and financial condition. As we have seen in prior periods, in the event of severe volatility in exchange rates, these exposures can increase, and the impact on our results of operations and financial condition can be more pronounced. In addition, the current environment and the increasingly global nature of our business have made hedging these exposures more complex and costly.

To reduce the impact of this earnings volatility, we hedge our foreign currency exposure by entering into foreign currency forward contracts on several of our largest foreign currency exposures, including the Singaporean Dollar, the British Pound Sterling, the Polish Zloty, the Australian Dollar, the Indian Rupee, the Brazilian Real, and the Swedish Krona. Although we have increased and may continue to increase the scope, complexity and duration of our foreign exchange risk management strategy, our current or future hedging activities may not sufficiently protect us from the adverse effects of currency exchange rate movements. Moreover, we make a number of estimates in conducting hedging activities, including in some cases the level of future bookings, cancellations, refunds, customer stay patterns and payments in foreign currencies. In the event those estimates differ significantly from actual results, we could experience greater volatility as a result of our hedging activities.

The terms of our debt covenants could limit our discretion in operating our business and any failure to comply with such covenants could result in the default of all of our debt.

The agreements governing our indebtedness contain and the agreements governing our future indebtedness will likely contain various covenants, including those that restrict our or our subsidiaries’ ability to, among other things:

These covenants may limit our ability to effectively operate our businesses or maximize stockholder value. In addition, our Amended and Restated Credit Agreement requires that we meet certain financial tests, including the maintenance of a leverage ratio and a minimum net worth. Our ability to satisfy these tests may be affected by factors and events beyond our control, and we may be unable to meet such tests in the future.

Any failure to comply with the restrictions of our Amended and Restated Credit Agreement, the indentures governing our senior secured notes due 2023 or any agreement governing our other indebtedness may result in an event of default under those agreements. Such default may allow the creditors to accelerate the related debt, which may trigger cross-acceleration or cross-default provisions in other debt. In addition, lenders may be able to terminate any commitments they had made to supply us with further funds.

We are updating our enterprise resource planning system, and problems with the design or implementation of this system could interfere with our business and operations.

We are continuing to implement a project to consolidate our business technology infrastructure to a single global ERP system. We expect to invest capital and human resources in the design and implementation of the ERP system, which may be disruptive to our underlying business. Any disruptions, delays or deficiencies in the design and implementation of the ERP system, particularly ones that impact our financial reporting and accounting systems, could adversely affect our business. Even if we do not encounter these adverse effects, the design and implementation of the ERP system may be more costly than we anticipate, which could negatively impact our financial position, results of operations and cash flows. In addition, the ERP system will be outsourced to a third-party provider, and any disruption to those outsourced systems may negatively impact our business. See “-We rely on the availability and performance of information technology services provided by third parties, including DXC, which manages a significant portion of our systems.”

Maintaining and improving our financial controls and the requirements of being a public company may strain our resources, divert management’s attention and affect our ability to attract and retain qualified board members.

As a public company, we are subject to the reporting requirements of the Exchange Act, the Sarbanes-Oxley Act of 2002 (the “Sarbanes-Oxley Act”), the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “Dodd-Frank Act”) and The NASDAQ Stock Market (“NASDAQ”) rules. The requirements of these rules and regulations have increased and will continue to significantly increase our legal and financial compliance costs, including costs associated with the hiring of additional personnel, making some activities more difficult, time-consuming or costly, and may also place undue strain on our personnel, systems and resources. The Exchange Act requires, among other things, that we file annual, quarterly and current reports with respect to our business and financial condition.

The Sarbanes-Oxley Act requires, among other things, that we maintain disclosure controls and procedures and internal control over financial reporting. Ensuring that we have adequate internal financial and accounting controls and procedures in place, as well as maintaining these controls and procedures, is a costly and time-consuming effort that needs to be re-evaluated frequently. Section 404 of the Sarbanes-Oxley Act (“Section 404”) requires that we annually evaluate our internal control over financial reporting to enable management to report on, and our independent auditors to audit as of the end of each fiscal year the effectiveness of those controls. In connection with the Section 404 requirements, both we and our independent registered public accounting firm test our internal controls and could, as part of that documentation and testing, identify material weaknesses, significant deficiencies or other areas for further attention or improvement.

Implementing any appropriate changes to our internal controls may require specific compliance training for our directors, officers and employees, require the hiring of additional finance, accounting and other personnel, entail substantial costs to modify our existing accounting systems, and take a significant period of time to complete. These changes may not, however, be effective in maintaining the adequacy of our internal controls, and any failure to maintain that adequacy, or consequent inability to produce accurate financial statements on a timely basis, could increase our operating costs and could materially impair our ability to operate our business. Moreover, adequate internal controls are necessary for us to produce reliable financial reports and are important to help prevent fraud. As a result, our failure to satisfy the requirements of Section 404 on a timely basis could result in the loss of investor confidence in the reliability of our financial statements, which in turn could cause the market value of our common stock to decline.

Various rules and regulations applicable to public companies make it more difficult and more expensive for us to maintain directors’ and officers’ liability insurance, and we may be required to accept reduced coverage or incur substantially higher costs to maintain coverage. If we are unable to maintain adequate directors’ and officers’ liability insurance, our ability to recruit and retain qualified officers and directors, especially those directors who may be deemed independent for purposes of the NASDAQ rules, will be significantly curtailed.

Concentration of ownership among our Principal Stockholders may prevent new investors from influencing significant corporate decisions and may result in conflicts of interest.

As of January 31, 2018, the Principal Stockholders (as defined below) own, in the aggregate, approximately 25% of our outstanding common stock and, consequently, have significant influence over us.

We are a party to an amended and restated Stockholders’ Agreement (as further amended and restated, the “Stockholders’ Agreement”) with the Silver Lake Funds, the TPG Funds and the Sovereign Co-Invest II (each as defined below). Pursuant to the Stockholders’ Agreement, each of the Silver Lake Funds and the TPG Funds currently has the right to designate for nomination two directors. In addition, the Silver Lake Funds and the TPG Funds also jointly have the right to designate one additional director who must qualify as independent under the NASDAQ rules and must meet the independence requirements of Rule 10A-3 of the Exchange Act so long as they collectively own at least 10% of their collective Closing Date Shares (as defined in the Stockholders’ Agreement). As a result, the Principal Stockholders are able to exercise significant influence over all matters requiring stockholder approval, including: the election of directors; approval of mergers or a sale of all or substantially all of our assets and other significant corporate transactions; and the amendment of our Certificate of Incorporation and our Bylaws. This concentration of influence may delay, deter or prevent acts that would be favored by our other stockholders, who may have interests different from those of our Principal Stockholders. In addition, this significant concentration of share ownership may adversely affect the trading price of our common stock because investors often perceive disadvantages in owning common stock in companies with Principal Stockholders.

“TPG” refers to TPG Global, LLC and its affiliates, the “TPG Funds” refer to one or more of TPG Partners IV, L.P. (“TPG Partners IV”), TPG Partners V, L.P. (“TPG Partners V”), TPG FOF V-A, L.P. (“TPG FOF V-A”) and TPG FOF V-B, L.P. (“TPG FOF V-B”), “Silver Lake” refers to Silver Lake Management Company, L.L.C. and its affiliates and “Silver Lake Funds” refer to either or both of Silver Lake Partners II, L.P. and Silver Lake Technology Investors II, L.P. “Sovereign Co-Invest II” refers to Sovereign Co-Invest II, LLC, an entity co-managed by TPG and Silver Lake. “Principal Stockholders” refer to the TPG Funds, the Silver Lake Funds and Sovereign Co-Invest II.

The market price of our common stock could decline due to the large number of outstanding shares of our common stock eligible for future sale.

Sales of substantial amounts of our common stock in the public market in future offerings, or the perception that these sales could occur, could cause the market price of our common stock to decline. These sales could also make it more difficult for us to sell equity or equity-related securities in the future, at a time and price that we deem appropriate. In addition, the additional sale of our common stock by our officers, directors and Principal Stockholders in the public market, or the perception that these sales may occur, could cause the market price of our common stock to decline.

We may issue shares of our common stock or other securities from time to time as consideration for, or to finance, future acquisitions and investments or for other capital needs. We cannot predict the size of future issuances of our shares or the effect, if any, that future sales and issuances of shares would have on the market price of our common stock. If any such acquisition or investment is significant, the number of shares of common stock or the number or aggregate principal amount, as the case may be, of other securities that we may issue may in turn be substantial and may result in additional dilution to our stockholders. We may also grant registration rights covering shares of our common stock or other securities that we may issue in connection with any such acquisitions and investments.

To the extent that any of us, our executive officers, directors or the Principal Stockholders sell, or indicate an intent to sell, substantial amounts of our common stock in the public market, the trading price of our common stock could decline significantly.

Our ability to pay regular dividends to our stockholders is subject to the discretion of our board of directors and may be limited by our holding company structure and applicable provisions of Delaware law.

We intend to continue to pay quarterly cash dividends on our common stock. However, our board of directors may, in its sole discretion, change the amount or frequency of dividends or discontinue the payment of dividends entirely. In addition, because we are a holding company with no material direct operations, we are dependent on loans, dividends and other payments from our operating subsidiaries to generate the funds necessary to pay dividends on our common stock. We expect to cause our subsidiaries to make distributions to us in an amount sufficient for us to pay dividends. However, their ability to make such distributions will be subject to their operating results, cash requirements and financial condition, the applicable provisions of Delaware law that may limit the amount of funds available for distribution and our ability to pay cash dividends, compliance with covenants and financial ratios related to existing or future indebtedness, including under our Amended and Restated Credit Agreement, our senior secured notes due in 2023, and other agreements with third parties. In addition, each of the companies in our corporate chain must manage its assets, liabilities and working capital in order to meet all of its cash obligations, including the payment of dividends or distributions. As a consequence of these various limitations and restrictions, we may not be able to make, or may have to reduce or eliminate, the payment of dividends on our common stock. Any change in the level of our dividends or the suspension of the payment thereof could adversely affect the market price of our common stock.