PART I

Semisubmersibles are floating vessels that can be partially submerged by means of a water ballast system such that the lower column sections and pontoons are below the water surface during drilling operations.  Semisubmersibles are known for stability, making them well suited for operating in rough sea conditions.  Semisubmersible floaters are capable of maintaining their position over a well either through dynamic positioning or the use of mooring systems.  Although most semisubmersible rigs are relocated with the assistance of tugs, some units are self‑propelled and move between locations under their own power when afloat on pontoons.  Five of our 22 semisubmersibles are equipped with dual‑activity technology and also have mooring capability.  Two of these five dual-activity units are custom‑designed, high capacity semisubmersible drilling rigs, equipped for year‑round operations in harsh environments, including those of the Norwegian continental shelf and sub‑Arctic waters.

Fleet categories —We further categorize the drilling units of our fleet as follows: (1) “ultra‑deepwater floaters,” (2) “harsh environment floaters” and (3) “midwater floaters”.  Ultra‑deepwater floaters are equipped with high‑pressure mud pumps and are capable of drilling in water depths of 4,500 feet or greater.  Harsh environment floaters are capable of drilling in harsh environments in water depths between 1,500 and 10,000 feet and have greater displacement, which offers larger variable load capacity, more useable deck space and better motion characteristics.  Midwater floaters are generally comprised of those non‑high‑specification semisubmersibles that have a water depth capacity of less than 4,500 feet.

As of February 11, 2019, we owned and operated a fleet of 49 rigs, excluding five newbuilds under construction, as follows:

Fleet status —Depending on market conditions, we may idle or stack non‑contracted rigs.  An idle rig is between drilling contracts, readily available for operations, and operating costs are typically at or near normal operating levels.  A stacked rig typically has reduced operating costs, is staffed by a reduced crew or has no crew and is (a) preparing for an extended period of inactivity, (b) expected to continue to be inactive for an extended period, or (c) completing a period of extended inactivity.  Stacked rigs will continue to incur operating costs at or above normal operating levels for approximately 30 days following initiation of stacking.  Some idle rigs and all stacked rigs require additional costs to return to service.  The actual cost to return to service, which in many instances could be significant and could fluctuate over time, depends upon various factors, including the availability and cost of shipyard facilities, the cost of equipment and materials and the extent of repairs and maintenance that may ultimately be required.  We consider these factors, together with market conditions, length of contract, dayrate and other contract terms, when deciding whether to return a stacked rig to service.  We may not return some stacked rigs to work for drilling services.

Drilling units —The following tables, presented as of February 11, 2019, provide certain specifications for our rigs.  Unless otherwise noted, the stated location of each rig indicates either the current drilling location, if the rig is operating, or the next operating location, if the rig is in shipyard with a follow‑on contract.  The dates provided represent the expected time of completion, the year placed into service, and, if applicable, the year of the most recent upgrade.  As of February 11, 2019, we owned all of the drilling rigs in our fleet noted in the tables below, except for the following: (1) the harsh environment floater Transocean Norge , which is under construction and owned through our 33.0 percent ownership interest in Orion Holdings (Cayman) Limited, and (2) the ultra‑deepwater floater Petrobras 10000 , which is subject to a capital lease through August 2029.

(c) To be equipped with two blowout preventers.

(d) Designed to accommodate a future upgrade to 20,000 pounds psi blowout preventers.

(e) To be equipped with two 20,000 pounds psi blowout preventers.

(f) To be equipped with mooring equipment.

Markets

Our operations are geographically dispersed in oil and gas exploration and development areas throughout the world.  We operate in a single, global offshore drilling market, as our drilling rigs are mobile assets and are able to be moved according to prevailing market conditions.  We may mobilize our drilling rigs between regions for a variety of reasons, including to respond to customer contracting requirements or to capture demand in another locale.  Consequently, we cannot predict the percentage of our revenues that will be derived from particular geographic areas in future periods.  As of February 11, 2019, our drilling fleet, including stacked and idle rigs, but excluding rigs under construction, was located in the Norwegian North Sea (nine units), the United States (“U.S.”) Gulf of Mexico (seven units), Trinidad (six units), Greece (five units), United Kingdom (“U.K.”) North Sea (five units), Angola (two units), Canada (two units), India (two units), Spain (two units), Australia (one unit), Brazil (one unit), Brunei (one unit), China (one unit), Equatorial Guinea (one unit), Ivory Coast (one unit), Malaysia (one unit), Mexican Gulf of Mexico (one unit) and Romania (one unit).

We categorize the market sectors in which we operate as follows: (1) ultra-deepwater and deepwater, (2) harsh environment and (3) midwater.  These market sectors, collectively known as the floater market, are serviced by our drillships and semisubmersibles, 14 of which are suited to work in harsh environments.  We generally view the ultra-deepwater and deepwater market sector as water depths beginning at 4,500 feet and extending to the maximum water depths in which rigs are capable of drilling, which is currently up to 12,000 feet.  The midwater market sector services water depths from approximately 300 feet to approximately 4,500 feet.  The harsh environment market sector services regions that are more challenged by lower temperatures, harsher weather conditions and water currents.

The market for offshore drilling rigs and related services reflects oil companies’ demand for equipment for drilling exploration, appraisal and development wells and for performing maintenance on existing production wells.    Activity levels of exploration and production (“E&P”) companies and their associated capital expenditures are largely driven by the worldwide demand for energy, including crude oil and natural gas.  Worldwide energy supply and demand drives oil and natural gas prices, which, in turn, impact E&P companies’ ability to fund investments in exploration, development and production activities.

In recent years, the industry has experienced a severe, prolonged cyclical downturn.  Multiple years of volatile and generally weak commodity prices have resulted in our customers delaying offshore investment decisions and postponing exploration and production programs.  Structural efficiency gains implemented by industry participants in reaction to the downturn have given customers more flexibility to progress exploration and development plans in a lower commodity pricing environment, which resulted in increased customer project sanctioning in 2018.  We anticipate this trend of increased project sanctioning to continue in 2019 as our customers realize improved offshore economics, making them less sensitive to market volatility, and sharpening their focus on exploration and reserve replacement.  In markets requiring harsh environment floating drilling rigs, such as the Norwegian North Sea and eastern Canada, the limited supply of these specialized rigs has resulted in improved fleet utilization, which has caused increased dayrates on high‑specification rigs being tendered for new work over the past year.  Outside of harsh environment markets, however, persistent excess supply of ultra‑deepwater floaters relative to demand has delayed improvement of dayrates.  As the hydrocarbon supply‑demand balance improves, we expect sustained improvement of oil prices, ultimately resulting in greater demand for ultra‑deepwater drilling rigs and improvement of dayrates.

Our recent acquisitions of Songa and Ocean Rig have significantly enhanced our high‑specification asset portfolio.  The Songa acquisition improved our fleet profile with harsh environment units for which we have already seen improved demand.  The Ocean Rig acquisition further improved our fleet profile by adding high‑specification ultra‑deepwater units that we expect to be in high demand as the market improves and the offshore drilling industry continues to prioritize the most modern and capable assets.  We have also made concerted efforts since the beginning of the downturn to high‑grade our fleet through divestment of lower‑specification assets.  During the years ended December 31, 2018, 2017 and 2016, we sold for scrap value eight, three and 11 drilling units, respectively, and at December 31, 2018, we had five additional rigs classified as held for sale for scrap value.

Longer term, our outlook for the offshore drilling sector remains positive, particularly for high‑specification assets.  Prior to the downturn, Brazil, the U.S. Gulf of Mexico, and West Africa emerged as key ultra‑deepwater market sectors, and licensing activity demonstrated an increased interest in deepwater fields as E&P companies looked to explore new prospects.  We expect deepwater oil and gas production will continue to be a part of the long‑term strategy for E&P companies as they strive to replace reserves to meet global demand for hydrocarbons.  As our customers implement the structural efficiency gains, we anticipate additional projects will be approved.  Typically, these projects are technically demanding due to factors such as water depth, complex well designs, deeper drilling depth, high pressure and temperature, sub‑salt, harsh environments, and heightened regulatory standards; therefore, they require sophisticated drilling units.  Generally, ultra‑deepwater rigs are the most modern, technologically advanced class of the offshore fleet and have capabilities that are attractive to E&P companies operating in deeper water depths, other challenging environments or with complex well designs.  See “Item 1A. Risk Factors—Risks related to our business.”

Contract Drilling Services

Our contracts to provide offshore drilling services are individually negotiated and vary in their terms and conditions.  We obtain most of our drilling contracts through competitive bidding against other contractors and direct negotiations with operators.  Drilling contracts generally provide for payment on a dayrate basis, with higher rates for periods while the drilling unit is operating and lower rates or

zero rate for periods of mobilization or when drilling operations are interrupted or restricted by equipment breakdowns, adverse environmental conditions or other conditions beyond our control.  A dayrate drilling contract generally extends over a period of time covering either the drilling of a single well or group of wells or covering a stated term.  At December 31, 2018, our contract backlog was approximately $12.5 billion, representing an increase of 32 percent and seven percent, respectively, compared to the contract backlog at December 31, 2017 and 2016, which was $9.5 billion and $11.7 billion, respectively.  See “Part II. Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Performance and Other Key Indicators.”

Certain of our drilling contracts may be cancelable for the convenience of the customer upon payment of an early termination payment.  Such payments, however, may not fully compensate us for the loss of the contract.  Contracts also customarily provide for either automatic termination or termination at the option of the customer, typically without the payment of any termination fee, under various circumstances such as non‑performance, in the event of extended downtime or impaired performance caused by equipment or operational issues, or periods of extended downtime due to force majeure events.  Many of these events are beyond our control.  The contract term in some instances may be extended by the customer exercising options for the drilling of additional wells or for an additional term.  Our contracts also typically include a provision that allows the customer to extend the contract to finish drilling a well‑in‑progress.  During periods of depressed market conditions, our customers may seek to renegotiate firm drilling contracts to reduce the term of their obligations or the average dayrate through term extensions, or may seek to repudiate their contracts.  Suspension of drilling contracts will result in the reduction in or loss of dayrate for the period of the suspension.  If our customers cancel some of our contracts and we are unable to secure new contracts on a timely basis and on substantially similar terms, if contracts are suspended for an extended period of time or if a number of our contracts are renegotiated, it could adversely affect our consolidated financial position, results of operations or cash flows.  See “Item 1A. Risk Factors—Risks related to our business—Our drilling contracts may be terminated due to a number of events, and, during depressed market conditions, our customers may seek to repudiate or renegotiate their contracts.”

Under dayrate drilling contracts, consistent with standard industry practice, our customers, as the operators, generally assume, and grant indemnity for, subsurface and well control risks, and their consequential damages.  Under all of our current drilling contracts, our customers, indemnify us for pollution damages in connection with reservoir fluids stemming from operations under the contract, and we indemnify our customers for pollution that originates above the surface of the water from the rig from substances in our control, such as diesel used onboard the rig or other fluids stored onboard the rig.  Also, our customers indemnify us for consequential damages they incur, damage to the well or reservoir, loss of subsurface oil and gas and the cost of bringing the well under control.  However, our drilling contracts are individually negotiated, and the degree of indemnification we receive from our customers for the risks discussed above may vary from contract to contract, based on market conditions and customer requirements existing when the contract was negotiated.  In some instances, we have contractually agreed upon certain limits to our indemnification rights and can be responsible for damages up to a specified maximum dollar amount.  The nature of our liability and the prevailing market conditions, among other factors, can influence such contractual terms.  In most instances in which we are indemnified for damages to the well, we have the responsibility to redrill the well at a reduced dayrate.  Notwithstanding a contractual indemnity from a customer, there can be no assurance that our customers will be financially able to indemnify us or will otherwise honor their contractual indemnity obligations.  See “Item 1A. Risk Factors—Risks related to our business—Our business involves numerous operating hazards, and our insurance and indemnities from our customers may not be adequate to cover potential losses from our operations.”

The interpretation and enforceability of a contractual indemnity depends upon the specific facts and circumstances involved, as governed by applicable laws, and may ultimately need to be decided by a court or other proceeding, which will need to consider the specific contract language, the facts and applicable laws.  The law generally considers contractual indemnity for criminal fines and penalties to be against public policy.  Courts also restrict indemnification for criminal fines and penalties.  The inability or other failure of our customers to fulfill their indemnification obligations, or unenforceability of our contractual protections could have a material adverse effect on our consolidated financial position, results of operations or cash flows.

Significant Customers

We engage in offshore drilling services for most of the leading integrated oil companies or their affiliates, as well as for many government‑controlled oil companies and independent oil companies.  For the year ended December 31, 2018, our most significant customers were Royal Dutch Shell plc (together with its affiliates, “Shell”), Chevron Corporation (together with its affiliates, “Chevron”) and Equinor ASA (together with its affiliates, “Equinor”), representing approximately 26 percent, 21 percent and 18 percent, respectively, of our consolidated operating revenues.  No other customers accounted for 10 percent or more of our consolidated operating revenues in the year ended December 31, 2018.  Additionally, as of February 11, 2019, the customers with the most significant aggregate amount of contract backlog associated with our drilling contracts were Shell, Equinor and Chevron, representing approximately 45 percent, 28 percent and 15 percent, respectively, of our total contract backlog.  See “Item 1A. Risk Factors—Risks related to our business—We rely heavily on a relatively small number of customers and the loss of a significant customer or a dispute that leads to the loss of a customer could have an adverse effect on our consolidated financial position, results of operations or cash flows.”

Employees

We require highly skilled personnel to operate our drilling units.  Consequently, we conduct extensive personnel recruiting, training and safety programs.  At December 31, 2018, we had approximately 6,700 employees, including approximately 800 persons engaged through contract labor providers.  Approximately 34 percent of our total workforce, working primarily in Norway, Brazil, the U.K.

and Australia are represented by, and some of our contracted labor work is subject to, collective bargaining agreements, substantially all of which are subject to annual salary negotiation.  These negotiations could result in higher personnel expenses, other increased costs or increased operational restrictions, as the outcome of such negotiations affect the market for all offshore employees not just the union members.  Additionally, failure to reach agreement on certain key issues may result in strikes, lockouts or other work stoppages that may materially impact our operations.

Joint Venture, Agency and Sponsorship Relationships and Other Investments

In some areas of the world, local customs and practice or governmental requirements necessitate the formation of joint ventures with local participation since local laws or customs in those areas effectively mandate the establishment of a relationship with a local agent or sponsor.  When appropriate in these areas, we enter into agency or sponsorship agreements.  We may also enter into joint ventures for operational or investment purposes.  We may or may not control these joint ventures.  We participate in several joint venture companies, principally in the Cayman Islands, Angola, Indonesia, Malaysia and Nigeria.  At December 31, 2018, we held interests in certain joint venture companies in the Cayman Islands, Angola, Indonesia, Malaysia, Nigeria and other countries, the most significant of which were as follows:

We hold a 33.0 percent ownership interest in Orion Holdings (Cayman) Limited, an unconsolidated Cayman Islands exempted company formed to construct and own the newbuild harsh environment semisubmersible Transocean Norge .  Our partners, certain affiliates of Hayfin Capital Management LLP, own the remaining 67.0 percent ownership interest not owned by us.

We hold a 24 percent direct interest and a 36 percent indirect interest in Indigo Drilling Limited (“Indigo”), a consolidated Nigerian joint venture company formed to engage in drilling operations offshore Nigeria.  Our local partners, Mr. Fidelis Oditah and Mr. Chima Ibeneche, each hold a 12.5 percent direct interest, and our other partners, Mr. Joseph Obi and Mr. Ben Osuno, together own a 15 percent indirect interest in Indigo.

Technological Innovation

Since launching the offshore industry’s first jackup drilling rig in 1954, we have achieved a long history of technological innovations, including the first dynamically positioned drillship, the first rig to drill year‑round in the North Sea, the first 10,000‑ft. rated ultra‑deepwater drillship and the first semisubmersible rig for year‑round sub‑Arctic operations.  We have repeatedly achieved water depth world records in the past.  Twenty‑five drillships and three semisubmersibles in our existing fleet are, and our four drillships that are under construction will be, equipped with our patented dual‑activity technology, and two of our semisubmersibles are equipped with another form of dual-activity technology.  Dual-activity allows our rigs to perform simultaneous drilling tasks in a parallel rather than sequential manner and reduces critical path activity while improving efficiency in both exploration and development drilling.

We continue to develop and deploy industry‑leading technology.  In addition to our patented dual‑activity drilling technology, two of our drillships under construction will include industry‑leading hookload capability, hybrid power systems for reduced fuel consumption and reduced emissions as well as advanced generator protection for power plant reliability.  We are focused on a breakthrough drilling innovation program that includes a fault‑resistant and fault‑tolerant blowout preventer control system.  Nine drillships in our existing fleet are, and our four drillships that are under construction will be, outfitted with two blowout preventers and triple liquid mud systems.  Five drillships in our existing fleet are, and two of our drillships that are under construction will be, designed to accept 20,000 psi blowout preventers in the future, and we recently contracted one of the drillships under construction to be equipped as such.  Seven of our harsh environment semi‑submersibles are designed and constructed specifically to provide highly efficient performance in the Norwegian North Sea and in the Barents Sea.  We believe the continual improvement of, and effective use of, technology to meet or exceed our customers’ requirements is critical to maintain our competitive position within the contract drilling services industry.  Additionally, our digital transformation program delivers real‑time data feeds from equipment and processes, which is used to build machine health models.  These models allow us to systematically optimize equipment maintenance and achieve higher levels of operational efficiency.  This data‑driven approach, augmented by the size of our fleet, is helping us build a knowledge framework for sustainable process optimization.

Environmental Compliance

Our operations are subject to a variety of global environmental regulations.  We monitor our compliance with environmental regulation in each country of operation and, while we see an increase in general environmental regulation, we have made and will continue to make the required expenditures to comply with current and future environmental requirements.  We make expenditures to further our commitment to environmental improvement and the setting of global environmental standards.  We assess the environmental impacts of our business, focusing on the areas of greenhouse gas emissions, climate change, discharges and waste management.  Our actions are designed to reduce risk in our current and future operations, to promote sound environmental management and to create a proactive environmental program.  To date, we have not incurred material costs in order to comply with recent environmental legislation, and we do not believe that our compliance with such requirements will have a material adverse effect on our competitive position, consolidated results of operations or cash flows.  For a discussion of the effects of environmental regulation, see “Item 1A. Risk Factors—Risks related to our business—Compliance with or breach of environmental laws can be costly, expose us to liability and could limit our operations.”

Available Information

Our website address is  www.deepwater.com.  Information contained on or accessible from our website is not incorporated by reference into this annual report on Form 10‑K and should not be considered a part of this report or any other filing that we make with the U.S. Securities and Exchange Commission (“SEC”).  We make available on this website free of charge, our annual reports on Form 10‑K, quarterly reports on Form 10‑Q, current reports on Form 8‑K and amendments to those reports as soon as reasonably practicable after we electronically file those materials with, or furnish those materials to, the SEC.  You may also find on our website information related to our corporate governance, board committees and company code of business conduct and ethics.  The SEC also maintains a website, www.sec.gov , which contains reports, proxy statements and other information regarding SEC registrants, including us.  We intend to satisfy the requirement under Item 5.05 of Form 8‑K to disclose any amendments to our Code of Integrity and any waiver from any provision of our Code of Integrity by posting such information in the Governance page on our website at www.deepwater.com .

and may in the future idle or stack additional rigs or enter into lower dayrate drilling contracts in response to market conditions.  Idled or stacked rigs may remain out of service for extended periods of time.  During prior periods of high dayrates and rig utilization rates, we and other industry participants have responded to increased customer demand by increasing the supply of rigs through ordering the construction of new units.  The number of new units expected to be delivered without contracts, combined with the expected increase in the number of rigs in the global market completing contracts and becoming idle, has intensified and may further intensify price competition.  In periods of low oil and natural gas price levels, new construction has historically resulted in an oversupply of rigs and has caused a subsequent decline in dayrates and rig utilization rates, sometimes for extended periods of time.  Any further near‑term increase in the construction of new units would likely exacerbate the negative impact of increased supply on dayrates and rig utilization rates.  Additional rigs that remain under construction, and the entry into service of these new units will increase overall supply.  In an oversupplied market, we may have limited bargaining power to negotiate on more favorable terms.  Additionally, lower market dayrates and intense price competition may drive customers to seek to renegotiate existing contracts to lower dayrates in exchange for longer contract terms.  Lower dayrates and rig utilization rates could adversely affect our revenues and profitability.

As of February 11, 2019, we have 19 uncontracted rigs, including seven uncontracted rigs recently acquired in the Ocean Rig acquisition.  These rigs may remain out of service for extended periods of time.  We also have three additional rigs under construction that have not been contracted for work.  If we are unable to obtain drilling contracts for our uncontracted rigs, whether due to a prolonged offshore drilling market recovery or otherwise, it may have an adverse effect on our results of operations and cash flows, and we may not be able to realize the expected synergies and other benefits of the acquisition on the timeline currently expected or at all.

At February 11, 2019, our contract backlog was approximately $12.2 billion.  This amount represents the number of days remaining in the firm term of the drilling contract multiplied by the maximum contractual operating dayrate, excluding revenues for mobilization, demobilization and contract preparation or other incentive provisions, which are generally insignificant to our contract drilling revenues.  Our contract backlog includes amounts associated with our newbuild units that are currently under construction.  The contractual operating dayrate may be higher than the actual dayrate we ultimately receive or an alternative contractual dayrate, such as waiting on weather rate, repair rate, standby rate or force majeure rate, may apply under certain circumstances.  The contractual operating dayrate may also be higher than the actual dayrate we ultimately receive due to a number of factors, including rig downtime or suspension of operations.  Several factors could cause rig downtime or a suspension of operations, including: equipment breakdowns and other unforeseen engineering problems, labor strikes and other work stoppages, shortages of material and skilled labor, surveys by government and maritime authorities, periodic classification surveys, severe weather or harsh operating conditions, and force majeure events.

In certain drilling contracts, the dayrate may be reduced to zero if, for example, repairs extend beyond a stated period of time.  Our contract backlog includes only firm commitments, which are represented by signed drilling contracts or, in some cases, other definitive agreements awaiting contract execution.  We may not be able to realize the full amount of our contract backlog due to events beyond our control.  In addition, some of our customers have experienced liquidity issues in the past and these liquidity issues could be experienced again if commodity prices decline for an extended period of time.  Liquidity issues and other market pressures could lead our customers to seek bankruptcy protection or to seek to repudiate, cancel or renegotiate these agreements for various reasons (see “—Our drilling contracts may be terminated due to a number of events, and, during depressed market conditions, our customers may seek to repudiate or renegotiate their contracts”).  Our inability to realize the full amount of our contract backlog may have a material adverse effect on our consolidated financial position, results of operations or cash flows.

The offshore drilling markets in which we compete experience fluctuations in the demand for drilling services.  Our ability to renew expiring drilling contracts or obtain new drilling contracts depends on the prevailing or expected market conditions at the time of expiration.  As of February 11, 2019, we have 19 stacked or idle rigs and three ultra‑deepwater drillships under construction that do not have customer drilling contracts.  We also have nine existing drilling contracts for our rigs that are currently operating, which are scheduled to expire before December 31, 2019.  We may be unable to obtain drilling contracts for our rigs that are currently operating upon the expiration or termination of such contracts or obtain drilling contracts for our newbuilds, and there may be a gap in the operation of the rigs between the current contracts and subsequent contracts.  When oil and natural gas prices are low or it is expected that such prices will decrease in the future, we may be unable to obtain drilling contracts at attractive dayrates or at all.  We may not be able to obtain new drilling contracts in direct continuation with existing contracts or for our uncontracted newbuild units, or depending on prevailing market conditions, we may enter into drilling contracts at dayrates substantially below the existing dayrates or on terms otherwise less favorable compared to existing contract terms, which may have an adverse effect on our consolidated financial position, results of operations or cash flows.

Certain of our drilling contracts with customers may be cancelable at the option of the customer upon payment of an early termination payment.  Such payments may not, however, fully compensate us for the loss of the contract.  Drilling contracts also

customarily provide for either automatic termination or termination at the option of the customer, typically without the payment of any termination fee, under various circumstances such as non‑performance, as a result of significant downtime or impaired performance caused by equipment or operational issues, or sustained periods of downtime due to force majeure events.  Many of these events are beyond our control.  During periods of depressed market conditions, we are subject to an increased risk of our customers seeking to repudiate their contracts, including through claims of non‑performance.  We are at continued risk of experiencing early contract terminations in a weak commodity price environment as operators look to reduce their capital expenditures.  During the years ended December 31, 2017 and 2016, our customers early terminated or cancelled contracts for one and eight of our rigs, respectively.  Our customers’ ability to perform their obligations under their drilling contracts, including their ability to fulfill their indemnity obligations to us, may also be negatively impacted by an economic downturn.  Our customers, which include national oil companies, often have significant bargaining leverage over us.  If our customers cancel some of our contracts, and we are unable to secure new contracts on a timely basis and on substantially similar terms, if contracts are suspended for an extended period of time or if a number of our contracts are renegotiated, it could adversely affect our consolidated financial position, results of operations or cash flows.  See “Item 1. Business—Contract Drilling Services.”

We must make substantial capital and operating expenditures to maintain our active fleet or to reactivate our stacked or idle fleet.  These expenditures could increase as a result of changes in the cost of labor and materials, requirements of customers, the size of our fleet, the cost of replacement parts for existing rigs, the geographic location of the rigs and the length of drilling contracts.  Changes in offshore drilling technology, customer requirements for new or upgraded equipment and competition within our industry may require us to make significant capital expenditures in order to maintain our competitiveness and to execute our growth plan.  Changes in governmental regulations, safety or other equipment standards, as well as compliance with standards imposed by maritime self-regulatory organizations, may cause our capital expenditures to increase or require us to make additional unforeseen capital expenditures.  As a result of these factors, we may be required to take our rigs out of service for extended periods of time, with corresponding losses of revenues, in order to make such alterations or to add such equipment.  In the future, market conditions may not justify these expenditures or enable us to operate our older rigs profitably during the remainder of their economic lives.

If we are unable to fund capital expenditures with our cash flows from operations or proceeds from sales of non-strategic assets, we may be required to either incur additional borrowings or raise capital through the sale of debt or equity securities.  Our ability to access the capital markets may be limited by our financial condition at the time, perceptions of us or our industry, by changes in laws and regulations or interpretation thereof and by adverse market conditions resulting from, among other things, general economic conditions and contingencies and uncertainties that are beyond our control.  If we raise funds by issuing equity securities, existing shareholders may experience dilution.  Our failure to obtain the funds for necessary future capital expenditures could have a material adverse effect on our business and on our consolidated financial position, results of operations and cash flows.

At December 31, 2018 and 2017, our total debt was $10.0 billion and $7.4 billion, respectively, of which $2.6 billion and $1.4 billion, respectively, was secured.  This substantial level of debt and other obligations could have significant adverse consequences on our business and future prospects, including the following:

See “Item 7. Management’s Discussion and Analysis of Financial Conditions and Results of Operations—Liquidity and Capital Resources—Sources and uses of liquidity.”

Two credit rating agencies have rated our non‑credit enhanced senior unsecured long‑term debt (our “Debt Rating”) below investment grade.  Our Debt Ratings could have adverse consequences for our business and future prospects and could cause the following:

Our Debt Ratings have caused some of the effects listed above, and any further downgrades may cause or exacerbate, any of the effects listed above and could have an adverse effect on our business and financial condition.

We engage in offshore drilling services for most of the leading integrated oil companies or their affiliates, as well as for many government‑controlled oil companies and independent oil companies.  For the year ended December 31, 2018, our most significant customers were Shell, Chevron and Equinor, accounting for approximately 26 percent, 21 percent and 18 percent, respectively, of our total contract drilling revenues.  As of February 11, 2019, the customers with the most significant aggregate amount of contract backlog were Shell, Equinor and Chevron, representing approximately 45 percent, 28 percent and 15 percent, respectively, of our total contract backlog.  The loss of any of these customers or another significant customer, or a decline in payments under any of our drilling contracts, could, at least in the short term, have an adverse effect on our business and on our consolidated financial position, results of operations or cash flows.

In addition, our drilling contracts subject us to counterparty risks.  The ability of each of our counterparties to perform its obligations under a contract with us will depend on a number of factors that are beyond our control and may include, among other things, general economic conditions, the condition of the offshore drilling industry, prevailing prices for oil and natural gas, the overall financial condition of the counterparty, the dayrates received and the level of expenditures necessary to maintain drilling activities.  In addition, in depressed market conditions, such as we are currently experiencing, our customers may no longer need a drilling rig that is currently under contract or may be able to obtain a comparable drilling rig at a lower dayrate.  Should a counterparty fail to honor its obligations under an agreement with us, we could sustain losses, which could have an adverse effect on our business and on our consolidated financial position, results of operations or cash flows.

Worldwide financial and economic conditions could restrict our ability to access the capital markets at a time when we would like, or need, to access such markets, which could have an impact on our flexibility to react to changing economic and business conditions.  Worldwide economic conditions have in the past impacted, and could in the future impact, the lenders participating in our credit facilities and our customers, causing them to fail to meet their obligations to us.  If economic conditions preclude or limit financing from banking institutions participating in our credit facilities, we may not be able to obtain similar financing from other institutions.  A slowdown in economic activity could further reduce worldwide demand for energy and extend or worsen the current period of low oil and natural gas prices.  These potential developments, or market perceptions concerning these and related issues, could affect our consolidated financial position, results of operations or cash flows.  In addition, turmoil and hostilities in the Middle East, North Africa and other geographic areas and countries are adding to overall risk.  An extended period of negative outlook for the world economy could further reduce the overall demand for oil and natural gas and for our services.  A further decline in oil and natural gas prices or an extension of the current low oil and natural gas prices could reduce demand for our drilling services and have a material adverse effect on our consolidated financial position, results of operations or cash flows.

Our operating and maintenance costs will not necessarily fluctuate in proportion to changes in our operating revenues.  Costs for operating a rig are generally fixed or only semi‑variable regardless of the dayrate being earned.  In addition, should our rigs incur unplanned downtime while on contract or idle time between drilling contracts, we will not always reduce the staff on those rigs because we could use the crew to prepare the rig for its next contract.  During times of reduced activity, reductions in costs may not be immediate

because portions of the crew may be required to prepare rigs for stacking, after which time the crew members may be reassigned to active rigs or released.  As our rigs are mobilized from one geographic location to another, the labor and other operating and maintenance costs can vary significantly.  In general, labor costs increase primarily due to higher salary levels and inflation.  Equipment maintenance costs fluctuate depending upon the type of activity the unit is performing and the age and condition of the equipment, and these costs could increase for short or extended periods as a result of regulatory or customer requirements that raise maintenance standards above historical levels.  The amount of contract preparation and reactivation costs vary based on the scope and length of the contract preparation or reactivation project, and the recognition of such costs varies depending on the duration of the firm contractual period and other contract terms.

As of February 11, 2019, we had under construction four ultra‑deepwater drillships and one harsh environment semisubmersible, in which we have a partial ownership interest.  We also have a variety of other more limited shipyard projects at any given time.  These shipyard projects are subject to the risks of delay or cost overruns inherent in any such construction project resulting from numerous factors, including the following:

These factors may contribute to cost variations and delays in the delivery of our newbuild units and other rigs undergoing shipyard projects.  Delayed delivery of these units would impact contract commencement, resulting in a loss of revenues we could earn, and may also cause customers to terminate or shorten the term of the drilling contract for the rig pursuant to applicable late delivery clauses.  In the event of termination of any of these drilling contracts, we may not be able to secure a replacement contract on as favorable terms, if at all.

Our operations also rely on a significant supply of capital and consumable spare parts and equipment to maintain and repair our fleet.  We also rely on the supply of ancillary services, including supply boats and helicopters.  Our reliance on our suppliers, manufacturers and service providers to secure equipment, parts, components and sub‑systems used in our operations exposes us to volatility in the quality, prices and availability of such items.  Certain parts and equipment that we use in our operations may be available only from a small number of suppliers, manufacturers or service providers, or in some cases must be sourced through a single supplier, manufacturer or service provider.  A disruption in the deliveries from our suppliers, manufacturers or service providers, capacity constraints, production disruptions, price increases, quality control issues, recalls or other decreased availability of parts and equipment or ancillary services could adversely affect our ability to meet our commitments to customers, adversely impact our operations, increase our operating costs and result in increases in rig downtime and delays in the repair and maintenance of our fleet.

Our business in the offshore drilling industry is affected by laws and regulations relating to the energy industry and the environment, including international conventions and treaties, and regional, national, state, and local laws and regulations.  The offshore drilling industry depends on demand for services from the oil and gas exploration and production industry, and, accordingly, we are directly affected by the adoption of laws and regulations that, for economic, environmental or other policy reasons, curtail exploration and development drilling for oil and gas.  Compliance with such laws, regulations and standards, where applicable, may require us to make significant capital expenditures, such as the installation of costly equipment or operational changes, and may affect the resale values or useful lives of our rigs.  We may also incur additional costs in order to comply with other existing and future regulatory obligations, including, but not limited to, costs relating to air emissions, including greenhouse gases, the management of ballast waters, maintenance and inspection, development and implementation of emergency procedures and insurance coverage or other financial assurance of our ability to address pollution incidents.  Offshore drilling in certain areas has been curtailed and, in certain cases, prohibited because of concerns over protection of the environment.  These costs could have a material adverse effect on our consolidated financial position, results of operations or cash flows.  A failure to comply with applicable laws and regulations may result in administrative and civil penalties, criminal sanctions or the suspension or termination of our operations.

To the extent new laws are enacted or other governmental actions are taken that prohibit or restrict offshore drilling or impose additional environmental protection requirements that result in increased costs to the oil and gas industry, in general, or the offshore drilling industry, in particular, our business or prospects could be materially adversely affected.  The operation of our drilling rigs will require certain governmental approvals, some of which may involve public hearings and costly undertakings on our part.  We may not obtain such approvals or such approvals may not be obtained in a timely manner.  If we fail to timely secure the necessary approvals or permits, our customers may have the right to terminate or seek to renegotiate their drilling contracts to our detriment.  The amendment or modification of existing laws and regulations or the adoption of new laws and regulations curtailing or further regulating exploratory or development drilling and production of oil and gas and compliance with any such new legislation or regulations could have an adverse effect on our business or on our consolidated financial position, results of operations or cash flows.

As contract driller with operations in certain offshore areas, we may be liable for damages and costs incurred in connection with oil spills or waste disposals related to those operations, and we may also be subject to significant fines in connection with spills.  For example, an oil spill could result in significant liability, including fines, penalties and criminal liability and remediation costs for natural resource damages, as well as third-party damages, to the extent that the contractual indemnification provisions in our drilling contracts are not enforceable or otherwise sufficient, or if our customers are unwilling or unable to contractually indemnify us from these risks.  Additionally, we may not be able to obtain such indemnities in our future drilling contracts, and our customers may not have the financial capability to fulfill their contractual obligations to us.  Also, these indemnities may be held to be unenforceable in certain jurisdictions, as a result of public policy or for other reasons.  Laws and regulations protecting the environment have become more stringent in recent years, and may in some cases impose strict liability, rendering a person liable for environmental damage without regard to negligence.  These laws and regulations may expose us to liability for the conduct of or conditions caused by others or for acts that were in compliance with all applicable laws at the time they were performed.  The application of these requirements or the adoption of new requirements or measures could have a material adverse effect on our consolidated financial position, results of operations or cash flows.

We operate in various regions throughout the world, which may expose us to political and other uncertainties, including risks of:

Our non‑U.S. contract drilling operations are subject to various laws and regulations in certain countries in which we operate, including laws and regulations relating to the import and export, equipment and operation of drilling units, currency conversions and repatriation, oil and gas exploration and development, taxation and social contributions of offshore earnings and earnings of expatriate personnel.  We are also subject to the U.S. Treasury Department’s Office of Foreign Assets Control (“OFAC”) and other U.S. and non‑U.S. laws and regulations governing our international operations.  In addition, various state and municipal governments, universities and other investors have proposed or adopted divestment and other initiatives regarding investments including, with respect to state governments, by state retirement systems in companies that do business with countries that have been designated as state sponsors of terrorism by the U.S. State Department.  Failure to comply with applicable laws and regulations, including those relating to sanctions and export restrictions, may subject us to criminal sanctions or civil remedies, including fines, denial of export privileges, injunctions or seizures of assets.  Investors could view any potential violations of OFAC regulations negatively, which could adversely affect our reputation and the market for our shares.

Governments in some countries have become increasingly active in regulating and controlling the ownership of concessions and companies holding concessions, the exploration for oil and gas and other aspects of the oil and gas industries in their countries, including local content requirements for participating in tenders for certain drilling contracts.  Many governments favor or effectively require the awarding of drilling contracts to local contractors or require nonlocal contractors to employ citizens of, or purchase supplies from, a particular jurisdiction or require use of a local agent.  In addition, government action, including initiatives by OPEC, may continue to cause oil or gas price volatility.  In some areas of the world, this governmental activity has adversely affected the amount of exploration and development work by major oil companies and may continue to do so.

Certain of our drilling contracts are partially payable in local currency.  The amounts, if any, of local currency received under these drilling contracts may exceed our local currency needs, leading to an accumulation of excess local currency balances, which, in

certain instances, may be subject to either temporary blocking or other difficulties converting to U.S. dollars, our functional currency, or to other currencies in which we operate.  Excess amounts of local currency may be exposed to the risk of currency exchange losses.

The shipment of goods, services and technology across international borders subjects us to extensive trade laws and regulations.  Our import and export activities are governed by unique customs laws and regulations in each of the countries where we operate.  Moreover, many countries, including the U.S., control the import and export of certain goods, services and technology and impose related import and export recordkeeping and reporting obligations.  Governments also may impose economic sanctions against certain countries, persons and other entities that may restrict or prohibit transactions involving such countries, persons and entities, and we are also subject to the U.S. anti‑boycott law.

The laws and regulations concerning import and export activity, recordkeeping and reporting, import and export control and economic sanctions are complex and constantly changing.  These laws and regulations may be enacted, amended, enforced or interpreted in a manner materially impacting our operations.  Ongoing economic challenges may increase some governments’ efforts to enact, enforce, amend or interpret laws and regulations as a method to increase revenue.  Shipments can be delayed and denied import or export for a variety of reasons, some of which are outside our control and some of which may result from failure to comply with existing legal and regulatory regimes.  Shipping delays or denials could cause unscheduled operational downtime.

Our ability to operate worldwide depends on our ability to obtain the necessary visas and work permits for our personnel to travel in and out of, and to work in, the jurisdictions in which we operate.  Governmental actions in some of the jurisdictions in which we operate may make it difficult for us to move our personnel in and out of these jurisdictions by delaying or withholding the approval of these permits.  If we are not able to obtain visas and work permits for the employees we need to conduct our operations on a timely basis, we might not be able to perform our obligations under our drilling contracts, which could allow our customers to cancel the contracts.  If our customers cancel some of our drilling contracts, and we are unable to secure new drilling contracts on a timely basis and on substantially similar terms, it could have a material adverse effect on our business and on our consolidated financial position, results of operations or cash flows.

Our operations are subject to the usual hazards inherent in the drilling of oil and gas wells, such as, blowouts, reservoir damage, loss of production, loss of well control, lost or stuck drill strings, equipment defects, craterings, fires, explosions and pollution.  Contract drilling requires the use of heavy equipment and exposure to hazardous conditions, which may subject us to liability claims by employees, customers and other parties.  These hazards can cause personal injury or loss of life, severe damage to or destruction of property and equipment, pollution or environmental damage, claims by third parties or customers and suspension of operations.  Our offshore fleet is also subject to hazards inherent in marine operations, either while on site or during mobilization, such as capsizing, sinking, grounding, collision, piracy, damage from severe weather and marine life infestations.

The South China Sea, the Northwest Coast of Australia and the U.S. Gulf of Mexico are areas subject to typhoons, hurricanes or other extreme weather conditions on a relatively frequent basis, and our drilling rigs in these regions may be exposed to damage or total loss by these storms, some of which may not be covered by insurance.  The occurrence of these events could result in the suspension of drilling operations, damage to or destruction of the equipment involved and injury to or death of rig personnel.  Some experts believe global climate change could increase the frequency and severity of these extreme weather conditions.  Operations may also be suspended because of machinery breakdowns, abnormal drilling conditions, failure of subcontractors to perform or supply goods or services, or personnel shortages.  We customarily provide contract indemnity to our customers for certain claims that could be asserted by us relating to damage to or loss of our equipment, including rigs, and claims that could be asserted by us or our employees relating to personal injury or loss of life.

Damage to the environment could also result from our operations, particularly through spillage of hydrocarbons, fuel, lubricants or other chemicals and substances used in drilling operations, or extensive uncontrolled fires.  We may also be subject to property damage, environmental indemnity and other claims by oil and natural gas companies.  Drilling involves certain risks associated with the loss of control of a well, such as blowout, cratering, the cost to regain control of or redrill the well and remediation of associated pollution.  Our customers may be unable or unwilling to indemnify us against such risks.  In addition, a court may decide that certain indemnities in our current or future drilling contracts are not enforceable.  The law generally considers contractual indemnity for criminal fines and penalties to be against public policy, and the enforceability of an indemnity as to other matters may be limited.

Our insurance policies and drilling contracts contain rights to indemnity that may not adequately cover our losses, and we do not have insurance coverage or rights to indemnity for all risks.  We have two main types of insurance coverage: (1) hull and machinery coverage for physical damage to our property and equipment and (2) excess liability coverage, which generally covers offshore risks, such as personal injury, third‑party property claims, and third‑party non‑crew claims, including wreck removal and pollution.  We generally have no hull and machinery insurance coverage for damages caused by named storms in the U.S. Gulf of Mexico.  We maintain per occurrence deductibles that generally range up to $10 million for various third‑party liabilities, and we self-insure $50 million of the $750 million excess liability coverage through our wholly owned captive insurance company.  We also retain the risk for any liability that exceeds our excess liability coverage.  However, pollution and environmental risks generally are not completely insurable.

If a significant accident or other event occurs that is not fully covered by our insurance or by an enforceable or recoverable indemnity, the occurrence could adversely affect our consolidated financial position, results of operations or cash flows.  The amount of our insurance may also be less than the related impact on enterprise value after a loss.  Our insurance coverage will not in all situations provide sufficient funds to protect us from all liabilities that could result from our drilling operations.  Our coverage includes annual aggregate policy limits.  As a result, we generally retain the risk for any losses in excess of these limits.  We generally do not carry insurance for loss of revenue, and certain other claims may also not be reimbursed by insurance carriers.  Any such lack of reimbursement may cause us to incur substantial costs.  In addition, we could decide to retain more risk in the future, resulting in higher risk of losses, which could be material.  Moreover, we may not be able to maintain adequate insurance in the future at rates that we consider reasonable or be able to obtain insurance against certain risks.

Following the Macondo well incident, enhanced governmental safety and environmental requirements applicable to our operations were adopted for drilling in the U.S. Gulf of Mexico.  In order to obtain drilling permits, operators must submit applications that demonstrate compliance with the enhanced regulations, which require independent third‑party inspections, certification of well design and well control equipment and emergency response plans in the event of a blowout, among other requirements.  Operators have had, and may in the future have, difficulties obtaining drilling permits in the U.S. Gulf of Mexico.  In addition, the oil and gas industry has adopted new equipment and operating standards, such as the American Petroleum Institute Standard 53, related to the installation and testing of well control equipment.  These safety and environmental guidelines and standards and any new guidelines or standards the U.S. government or industry may issue or any other steps the U.S. government or industry may take, could disrupt or delay operations, increase the cost of operations, increase out‑of‑service time or reduce the area of operations for drilling rigs in the U.S. and non‑U.S. offshore areas.

Other governments could take similar actions related to implementing new safety and environmental regulations in the future.  Additionally, some of our customers have elected to voluntarily comply with some or all the inspections, certification requirements and safety and environmental guidelines on rigs operating outside of the U.S. Gulf of Mexico.  Additional governmental regulations and requirements concerning licensing, taxation, equipment specifications and training requirements or the voluntary adoption of such requirements or guidelines by our customers could increase the costs of our operations, increase certification and permitting requirements, increase review periods and impose increased liability on offshore operations.  The continuing effects of the enhanced regulations may also decrease the demand for drilling services, negatively affect dayrates and increase out‑of‑service time, which could ultimately have an adverse effect on our revenues and profitability.

We have undertaken and continue to seek appropriate opportunities for restructuring our organization, engaging in strategic divestitures, acquisitions and other business combinations in order to optimize our fleet and strengthen our competitiveness.  We face risks arising from these activities, which could adversely affect our ability to achieve our strategic goals, such as the following:

We depend on the continuing efforts of key members of our management, as well as other highly skilled personnel, to operate and provide technical services and support for our business worldwide.  Historically, competition for the personnel required for drilling operations has intensified as the number of rigs activated, added to worldwide fleets or under construction increased, leading to shortages of qualified personnel in the industry and creating upward pressure on wages and higher turnover.  We may experience a reduction in the experience level of our personnel as a result of any increased turnover and ongoing staff reduction initiatives, which could lead to higher downtime and more operating incidents, which in turn could decrease revenues and increase costs.  If increased competition for qualified personnel were to intensify in the future we may experience increases in costs or limits on operations.

Approximately 34 percent of our total workforce, primarily employed in Norway, Brazil, the U.K. and Australia, are represented by, and some of our contracted labor work is subject to, collective bargaining agreements, substantially all of which are subject to annual salary negotiation.  These negotiations could result in higher personnel expenses, other increased costs or increased operational

restrictions as the outcome of such negotiations affect the market for all offshore employees not just the union members.  Legislation has been introduced in the U.S. Congress that could encourage additional unionization efforts in the U.S., as well as increase the chances that such efforts succeed.  Additional unionization efforts, if successful, new collective bargaining agreements or work stoppages could materially increase our labor costs and operating restrictions.

The U.S. Foreign Corrupt Practices Act (“FCPA”), the U.K. Bribery Act 2010 (“Bribery Act”) and similar anti‑bribery laws in other jurisdictions, generally prohibit companies and their intermediaries from making improper payments for the purpose of obtaining or retaining business.  We operate in many parts of the world that have experienced corruption to some degree and, in certain circumstances, strict compliance with anti‑bribery laws may conflict with local customs and practices.  If we are found to be liable for violations under the FCPA, the Bribery Act or other similar laws, either due to our acts or omissions or due to the acts or omissions of others, including our partners in our various joint ventures, we could suffer from civil and criminal penalties or other sanctions, which could have a material adverse effect on our business or our consolidated financial position and results of operations.  In addition, investors could negatively view potential violations, inquiries or allegations of misconduct under the FCPA, the Bribery Act or similar laws, which could adversely affect our reputation and the market for our shares.

We could also face fines, sanctions and other penalties from authorities in the relevant jurisdictions, including prohibition of our participating in or curtailment of business operations in those jurisdictions and the seizure of rigs or other assets.  Additionally, we could face claims by agents, shareholders, debt holders, or other interest holders or constituents of our company.  Further, disclosure of the subject matter of any investigation could adversely affect our reputation and our ability to obtain new business with potential customers or retain existing business with our current customers, to attract and retain employees and to access the capital markets.  Our customers in relevant jurisdictions could seek to impose penalties or take other actions adverse to our interests, and we may be required to dedicate significant time and resources to investigate and resolve allegations of misconduct, regardless of the merit of such allegations.

Scientific studies have suggested that emissions of certain gases, including greenhouse gases, carbon dioxide and methane, contribute to warming of the earth’s atmosphere and other climatic changes.  In response to such studies, the issue of climate change and the effect of greenhouse gas emissions, in particular emissions from fossil fuels, is attracting increasing attention worldwide.  For example, in December 2015, 195 nations adopted the Paris Agreement, which went into effect in November 2016.  The Paris Agreement aims to limit increases in global temperatures to well below two degrees Celsius.  While the greenhouse gas emission reductions called for by the Paris Agreement are not binding, we expect continued and increased attention to climate change.  This attention has led, and we expect it to continue to lead, to additional regulations designed to reduce greenhouse gas emissions domestically and internationally.  Because our business depends on the level of activity in the offshore oil and gas industry, existing or future laws, regulations, treaties or international agreements related to greenhouse gases and climate change, including incentives to conserve energy or use alternative energy sources, could have a negative impact on our business if such laws, regulations, treaties or international agreements reduce the worldwide demand for oil and gas or limit drilling opportunities.  In addition, such laws, regulations, treaties or international agreements could result in increased compliance costs or additional operating restrictions, which may have an adverse effect on our business.

We are subject to a variety of disputes, investigations and litigation.  Certain of our subsidiaries are subject to and have been involved in litigation with certain of our customers.  We have subsidiaries that have issued debt under indentures that are subject to covenant compliance, some of which have been accused of breaching certain requirements of such covenants (see “Part II. Item 8. Financial Statements and Supplementary Data—Notes to Consolidated Financial Statements—Note 13—Commitments and Contingencies—Global Marine litigation”).  Certain of our subsidiaries are named as defendants in numerous lawsuits alleging personal injury as a result of exposure to asbestos or toxic fumes or resulting from other occupational diseases, such as silicosis, and various other medical issues that can remain undiscovered for a considerable amount of time.  Some of these subsidiaries that have been put on notice of potential liabilities have no assets.  Certain subsidiaries are subject to litigation relating to environmental damage.  Our patent for dual‑activity technology has been successfully challenged in certain jurisdictions.  We are also subject to a number of significant tax disputes.  We cannot predict the outcome of the cases involving those subsidiaries or the potential costs to resolve them.  Insurance may not be applicable or sufficient in all cases, insurers may not remain solvent and policies may not be located.  Suits against non‑asset‑owning subsidiaries have and may in the future give rise to alter ego or successor‑in‑interest claims against us and our asset‑owning subsidiaries to the extent a subsidiary is unable to pay a claim or insurance is not available or sufficient to cover the claims.  To the extent that one or more pending or future litigation matters is not resolved in our favor and is not covered by insurance, which could have an adverse effect on our financial position, results of operations or cash flows.

We depend on digital technologies to conduct our offshore and onshore operations, to collect payments from customers and to pay vendors and employees.  Our data protection measures and measures taken by our customers and vendors may not prevent

unauthorized access of information technology systems.  Threats to our information technology systems, and the systems of our customers and vendors, associated with cybersecurity risks and cyber‑incidents or attacks continue to grow.  Threats to our systems and our customers’ and vendors’ systems may derive from human error, fraud or malice on the part of employees or third parties, or may result from accidental technological failure.  In addition, breaches to our systems and systems of our customers and vendors could go unnoticed for some period of time.  Risks associated with these threats include disruptions of certain systems on our rigs; other impairments of our ability to conduct our operations; loss of intellectual property, proprietary information or customer and vendor data; disruption of our customers’ and vendors’ operations; loss or damage to our customer and vendor data delivery systems; and increased costs to prevent, respond to or mitigate cybersecurity events.  If such a cyber‑incident were to occur, it could have a material adverse effect on our business or on our consolidated financial position, results of operations or cash flows.

In addition, new laws and regulations governing data privacy and the unauthorized disclosure of confidential information, including the European Union General Data Protection Regulation and recent California legislation, pose increasingly complex compliance challenges and potentially elevate our costs.  Any failure by us to comply with these laws and regulations, including as a result of a security or privacy breach, could result in significant penalties and liabilities for us.  Additionally, if we acquire a company that has violated or is not in compliance with applicable data protection laws, we may incur significant liabilities and penalties as a result.

Acts of terrorism and social unrest, brought about by world political events or otherwise, have caused instability in the world’s financial and insurance markets in the past and may occur in the future.  Such acts could be directed against companies such as ours.  In addition, acts of terrorism, piracy and social unrest could lead to increased volatility in prices for crude oil and natural gas and could affect the markets for drilling services.  Insurance premiums could increase and coverage may be unavailable in the future.  Government regulations may effectively preclude us from engaging in business activities in certain countries.  These regulations could be amended to cover countries where we currently operate or where we may wish to operate in the future.  Our drilling contracts do not generally provide indemnification against loss of capital assets or loss of revenues resulting from acts of terrorism, piracy or political or social unrest.  We have limited insurance for our assets providing coverage for physical damage losses resulting from risks, such as terrorist acts, piracy, vandalism, sabotage, civil unrest, expropriation and acts of war, and we do not carry insurance for loss of revenues resulting from such risks.

Public health threats, such as Severe Acute Respiratory Syndrome, severe influenza and other highly communicable viruses or diseases, outbreaks of which have already occurred in various parts of the world in which we operate, could adversely impact our operations, the operations of our customers and the global economy, including the worldwide demand for oil and natural gas and the level of demand for our services.  The quarantine of personnel or inability to access our offices or rigs could adversely affect our operations.  Travel restrictions or operational problems in any part of the world in which we operate, or any reduction in the demand for drilling services caused by public health threats in the future, may materially impact our operations and have an adverse effect on our results of operations.

We believe these acquisitions will provide benefits to the combined company as described in our other filings with the SEC.  However, there is a risk that some or all of the expected benefits of either or both acquisitions may fail to materialize, or may not occur within the time periods anticipated.  The realization of such benefits may be affected by a number of factors, many of which are beyond our control, including but not limited to the strength or weakness of the economy and competitive factors in the areas where we do business, the effects of competition in the markets in which we operate, and the impact of changes in the laws and regulations regulating the offshore drilling industry or affecting domestic or foreign operations.  The challenge of coordinating previously separate businesses makes evaluating the business and future financial prospects of the combined company following the acquisition difficult.  The success of the acquisitions, including anticipated benefits and cost savings, will depend, in part, on our ability to successfully integrate the operations of each of these companies in a manner that results in various benefits, including, among other things, an expanded market reach and operating efficiencies, and that does not materially disrupt existing relationships nor result in decreased revenues or dividends.  Failure to realize the anticipated benefits of the acquisitions may impact the financial performance of the combined company.

We have incurred substantial costs in connection with the negotiation and completion of acquisitions of Songa and Ocean Rig.  We have incurred significant legal, advisory and financial services fees in connection with the process of negotiating and evaluating the terms of each acquisition.  Additional significant unanticipated costs may be incurred as we continue to combine and integrate the acquired businesses.  We also have incurred and will continue to incur transaction fees and costs related to formulating and implementing integration plans, including facilities and systems consolidation costs and employment-related costs.  We continue to assess the magnitude of these costs, and additional unanticipated costs may be incurred as we continue to integrate the companies’ businesses.  Although we expect that the elimination of duplicative costs, as well as the realization of other efficiencies related to the integration of the businesses, which should allow us to offset integration-related costs over time, this net benefit may not be achieved in the near term, or at

all (see the risk factor titled “We may not realize the anticipated benefits of the acquisition of Songa or Ocean Rig” above).  These costs described above, as well as other unanticipated costs and expenses, could have an adverse effect on our consolidated financial position, operating results and cash flows.

Other risks

At December 31, 2018, the carrying amount of our property and equipment was $20.4 billion, representing 80 percent of our total assets.  In accordance with our accounting policies, we review our property and equipment for impairment when events or changes in circumstances indicate that carrying amounts of our assets held and used may not be recoverable.  We also review the carrying amounts of assets at the time that we classify such assets as held for sale.  In the year ended December 31, 2018, we recognized an aggregate loss of $999 million associated with the impairment of certain assets that we determined were impaired at the time the assets were classified as held for sale.  In the year ended December 31, 2017, we recognized an aggregate loss of $1.4 billion associated with the impairment of certain assets that we determined were impaired at the time the assets were classified as held for sale and an aggregate loss of $94 million associated with the impairment of our midwater floater asset group.  Future expectations of lower dayrates or rig utilization rates or a significant change to the composition of one or more of our asset groups could result in the recognition of additional losses on impairment of our long‑lived asset groups if future cash flow expectations, based on information available to management at the time of measurement, indicate that the carrying amount of our asset groups may be impaired.

We are subject to changes in applicable tax laws, treaties or regulations in the jurisdictions in which we operate and earn income, and such changes could include laws or policies directed toward companies organized in jurisdictions with low tax rates.  A material change in the tax laws, treaties or regulations, or their interpretation or application, of any country in which we have significant operations, or in which we are incorporated or resident, could result in a higher effective tax rate on our worldwide earnings and such change could be significant to our financial results.  Switzerland, for example, has been carefully considering various tax reform proposals in response to certain guidance from and demands by the European Union (“EU”) and the Organization for Economic Co‑operation and Development (the “OECD”).  Some of these tax reform measures may be adopted into law and effective as early as 2019.  Similarly, the OECD issued its action plan of tax reform measures that called for member states to take action to prevent base erosion and profit shifting.  Some of these measures impact transfer pricing, requirements to qualify for tax treaty benefits, and the definition of permanent establishments depending on each jurisdiction’s adoption and interpretation of such proposals.  Respective countries have adopted various measures into their own tax laws.  In addition, the EU issued its Anti‑Tax Avoidance Directive in 2016 that required its member states to adopt specific tax reform measures by 2019.  Other tax jurisdictions in which we operate may consider implementing similar legislation.  Any material change to tax laws or policies, their interpretation or the adoption of new interpretations of existing laws and rulings in any of the jurisdictions in which we operate could result in a higher effective tax rate on our worldwide earnings and such change could have a significant adverse effect on our consolidated financial position, results of operations or cash flows.

We are subject to tax laws, treaties and regulations in the countries in which we operate and earn income.  Our income taxes are based on the applicable tax laws and tax rates in effect in the countries in which we operate and earn income as well as upon our operating structures in these countries.  Our income tax returns are subject to review and examination in these jurisdictions, and we do not recognize the benefit of income tax positions we believe are more likely than not to be disallowed upon challenge by a tax authority.  If any tax authority successfully challenges our operational structure, intercompany pricing policies or the taxable presence of our key subsidiaries in certain countries; or if the terms of certain income tax treaties are interpreted in a manner that is adverse to our structure; or if we lose a material tax dispute in any country, particularly in the U.S., India, Brazil or Nigeria, our effective tax rate on our worldwide earnings could increase substantially and our earnings and cash flows from operations could be materially adversely affected.  For example, we cannot be certain that the U.S. Internal Revenue Service (“IRS”) will not successfully contend that we or any of our key subsidiaries were or are engaged in a trade or business in the U.S. or that we or any of our key subsidiaries maintained or maintain a permanent establishment in the U.S.  The determination of the aforementioned, among other things, involves considerable uncertainty.  If we or any of our key subsidiaries were determined to have been engaged in a trade or business in the U.S. through a permanent establishment, then we could be subject to U.S. corporate income and additional branch profits taxes on the portion of our earnings effectively connected to such U.S. business during the period in which this was considered to have occurred.  If this occurs, our effective tax rate on worldwide earnings for that period could increase substantially, and our earnings and cash flows from operations for that period could be adversely affected.

A foreign corporation will be treated as a passive foreign investment company (“PFIC”) for U.S. federal income tax purposes if either (1) at least 75 percent of its gross income for any taxable year consists of certain types of passive income or (2) at least 50 percent of the average value of the corporation's assets produce or are held for the production of those types of passive income.  For purposes of these tests, passive income includes dividends, interest and gains from the sale or exchange of investment property and certain rents and royalties, but does not include income derived from performing services.

We believe that we have not been and will not be a PFIC with respect to any taxable year.  Our income from offshore contract drilling services should be treated as services income for purposes of determining whether we are a PFIC.  Accordingly, we believe that our income from our offshore contract drilling services should not constitute passive income, and the assets that we own and operate in connection with the production of that income should not constitute passive assets.  There is significant legal authority supporting this position, including statutory provisions, legislative history, case law and IRS pronouncements concerning the characterization, for other tax purposes, of income derived from services where a substantial component of such income is attributable to the value of the property or equipment used in connection with providing such services.  However, a prior case and an IRS pronouncement that relies on the case characterize income from time chartering of vessels as rental income rather than services income for other tax purposes.  The IRS has subsequently formally announced that it does not agree with the decision in that case.  Moreover, we believe that the terms of the time charters in the prior case differ in material respects from the terms of our drilling contracts with customers.  No assurance can be given that the IRS or a court will accept our position, and there is a risk that the IRS or a court could determine that we are a PFIC.

If we were treated as a PFIC for any taxable year, our U.S. shareholders would face adverse U.S. tax consequences.  Under the PFIC rules, unless a shareholder makes certain elections available under the Internal Revenue Code of 1986, as amended, and such elections could themselves have adverse consequences for the shareholder, the shareholder could be required to pay U.S. federal income tax at the highest applicable income tax rates on ordinary income upon the receipt of excess distributions, as defined for U.S. tax purposes, and upon any gain from the disposition of our shares, plus interest on such amounts, as if such excess distribution or gain had been recognized ratably over the shareholder’s holding period of our shares.  Additionally, under applicable statutory provisions, the preferential tax rate on qualified dividend income, which applies to dividends paid to non‑corporate shareholders, does not apply to dividends paid by a foreign corporation if the foreign corporation is a PFIC for the taxable year in which the dividend is paid or the preceding taxable year.

Under Swiss law, our shareholders may approve an authorized share capital that allows the board of directors to issue new shares without additional shareholder approval within a period of up to two years.  The authorized share capital is limited to a maximum of 50 percent of a company’s registered share capital.  The authorized share capital approved by our shareholders at the May 2018 annual general meeting will expire on May 18, 2020.  Accordingly, shareholders at our annual general meeting in May 2019 are not expected to be requested to approve an authorized share capital.  Our current authorized share capital is limited to approximately five percent of our registered share capital.  Additionally, subject to certain exceptions, Swiss law grants preemptive rights to existing shareholders to subscribe for new issuances of shares.  Further, Swiss law does not provide as much flexibility in the various terms that can attach to different classes of shares as the laws of some other jurisdictions.  Swiss law also reserves for shareholder approval certain corporate actions over which a board of directors would have authority in some other jurisdictions.  For example, dividends must be approved by shareholders.  These Swiss law requirements relating to our capital management may limit our flexibility, and situations may arise where greater flexibility would have provided substantial benefits to our shareholders.

Distributions to shareholders in the form of a par value reduction and dividend distributions out of qualifying additional paid‑in capital are not currently subject to the 35 percent Swiss federal withholding tax.  However, the Swiss withholding tax rules could also be changed in the future, and any such change may adversely affect us or our shareholders.  In addition, over the long term, the amount of par value available for us to use for par value reductions or the amount of qualifying additional paid‑in capital available for us to pay out as distributions is limited.  If we are unable to make a distribution through a reduction in par value, or out of qualifying additional paid‑in capital as shown on Transocean Ltd.’s standalone Swiss statutory financial statements, we may not be able to make distributions without subjecting our shareholders to Swiss withholding taxes.

Under Swiss tax law, repurchases of shares for the purposes of capital reduction are treated as a partial liquidation subject to a 35 percent Swiss withholding tax based on the difference between the repurchase price and the related amount of par value and the related amount of qualifying additional paid‑in capital, if any.  At our 2009 annual general meeting, our shareholders approved the repurchase of up to CHF 3.5 billion of our shares for cancellation under the share repurchase program.  If we repurchase shares, we expect to use an alternative procedure pursuant to which we repurchase shares via a “virtual second trading line” from market players, such as banks and institutional investors, who are generally entitled to receive a full refund of the Swiss withholding tax.  The use of such “virtual second trading line” with respect to share repurchase programs is subject to the approval of the competent Swiss tax and other authorities.  We may not be able to repurchase as many shares as we would like to repurchase for purposes of capital reduction on the “virtual second trading line” without subjecting the selling shareholders to Swiss withholding taxes.

The Swiss Federal Council Ordinance Against Excessive Compensation at Public Companies (the “Ordinance”), among other things, (a) requires a binding shareholder “say on pay” vote with respect to the compensation of members of our executive management and board of directors, (b) generally prohibits the making of severance, advance, transaction premiums and similar payments to members of our executive management and board of directors, and (c) requires the declassification of our board of directors and the amendment of our articles of association to specify various compensation‑related matters.  At our annual general meetings, our shareholders are required to approve the maximum aggregate compensation of (1) our board of directors for the period through the successive annual general meeting and (2) our executive management team for the following year.  The Ordinance further provides for criminal penalties against directors and members of executive management in case of noncompliance with certain of its requirements.  The Ordinance may negatively affect our ability to attract and retain executive management and members of our board of directors.

We are required, from time to time, to evaluate the carrying amount of our investments in affiliates, as presented on our Swiss standalone balance sheet.  If we determine that the carrying amount of any such investment exceeds its fair value, we may conclude that such investment is impaired.  The recognized loss associated with such a non-cash impairment could result in our net assets no longer covering our statutory share capital and statutory capital reserves.  Under Swiss law, if our net assets cover less than 50 percent of our statutory share capital and statutory capital reserves, the board of directors must convene a general meeting of shareholders and propose measures to remedy such a capital loss.  The appropriate measures depend on the relevant circumstances and the magnitude of the recognized loss and may include seeking shareholder approval for offsetting the aggregate loss, or a portion thereof, with our statutory capital reserves including qualifying additional paid-in capital otherwise available for distributions to shareholders or raising new equity.  Depending on the circumstances, we may also need to use qualifying additional paid‑in capital available for distributions in order to reduce our accumulated net loss and such use might reduce our ability to make distributions without subjecting our shareholders to Swiss withholding tax.  These Swiss law requirements could limit our flexibility to swiftly implement certain initiatives or strategies.

Our articles of association and Swiss law contain provisions that could prevent or delay an acquisition of the company by means of a tender offer, a proxy contest or otherwise.  Actions taken under such provisions may adversely affect prevailing market prices for our shares, and could, among other things:

In June 2016, a majority of voters in the U.K. elected to withdraw from the European Union in a national referendum, and in March 2017, the government of the U.K. formally initiated the process.  The referendum was advisory, and the terms of any withdrawal are subject to a negotiation period that could last at least two years after the March 2017 initiation.  Though the U.K. withdrawal from the European Union is scheduled to occur in March 2019, there is currently no agreement in place regarding the withdrawal, creating significant uncertainty about the future relationship between the U.K. and the European Union, including with respect to the laws and regulations that will apply as the U.K. determines which European Union‑derived laws to replace or replicate in the event of a withdrawal.  The referendum has also given rise to calls for the governments of other European Union member states to consider withdrawal.  These developments, or the perception that any of them could occur, have had and may continue to have an adverse effect on global economic

conditions and the stability of global financial markets, and may significantly reduce global market liquidity and restrict the ability of key market participants to operate in certain financial markets.  Any of these factors could depress economic activity and restrict our access to capital, which could have a material adverse effect on our business and on our consolidated financial position, results of operations or cash flows.

Jeremy D. Thigpen is President and Chief Executive Officer and a member of the Company’s board of directors.  Before joining the Company in this position in April 2015, Mr. Thigpen served as Senior Vice President and Chief Financial Officer at National Oilwell Varco, Inc. from December 2012 to April 2015.  At National Oilwell Varco, Inc., Mr. Thigpen also served as President, Downhole and Pumping Solutions from August 2007 to December 2012, as President of the Downhole Tools Group from May 2003 to August 2007 and as manager of the Downhole Tools Group from April 2002 to May 2003.  From 2000 to 2002, Mr. Thigpen served as the Director of Business Development and Special Assistant to the Chairman for National Oilwell Varco, Inc.  Mr. Thigpen earned a Bachelor of Arts degree in Economics and Managerial Studies from Rice University in 1997, and he completed the Program for Management Development at Harvard Business School in 2001.

Keelan Adamson is Executive Vice President and Chief Operations Officer of the Company.  Before being named to his current position in August 2018, Mr. Adamson served as Senior Vice President, Operations from October 2017 to July 2018 and as Senior Vice President, Operations Integrity and HSE, from June 2015 to October 2017.  Since 2010, Mr. Adamson served in multiple executive positions with responsibilities spanning Engineering and Technical Services, Major Capital Projects, Human Resources, and more recently, Operations Integrity and HSE.  Mr. Adamson started his career as a drilling engineer with BP Exploration in 1991 and joined Transocean in July 1995.  In addition to several management assignments in the U.K., Asia, and Africa, he also held leadership roles in Sales and Marketing, Well Construction and Technology, and as Managing Director for operations in North America, Canada and Trinidad.  Mr. Adamson earned a Bachelor's degree in Aeronautical Engineering from The Queens University of Belfast and completed the Advanced Management program at Harvard Business School in 2016.

Howard E. Davis is Executive Vice President, Chief Administrative Officer and Chief Information Officer of the Company.  Before joining the Company in this position in August 2015, Mr. Davis served as Senior Vice President, Chief Administrative Officer and Chief Information Officer of National Oilwell Varco, Inc. from March 2005 to April 2015 and as Vice President, Chief Administrative Officer and Chief Information Officer from August 2002 to March 2005.  Mr. Davis earned a Bachelor’s degree from University of Kentucky in 1980, and he completed the Advanced Management Program at Harvard Business School in 2005.

Brady K. Long is Executive Vice President and General Counsel of the Company.  Before being named to his current position in March 2018, Mr. Long served as Senior Vice President and General Counsel from November 2015 to March 2018.  From 2011 to November 2015, when Mr. Long joined the Company, he served as Vice President—General Counsel and Secretary of Ensco plc, which acquired Pride International, Inc. where he had served as Vice President, General Counsel and Secretary since August 2009.  Mr. Long joined Pride International, Inc. in June 2005 as Assistant General Counsel and served as Chief Compliance Officer from June 2006 to February 2009.  He was director of Transocean Partners LLC from May 2016 until December 2016.  Mr. Long previously practiced corporate and securities law with the law firm of Bracewell LLP.  He earned a Bachelor of Arts degree from Brigham Young University in 1996 and a Juris Doctorate degree from the University of Texas School of Law in 1999.

Mark L. Mey is Executive Vice President and Chief Financial Officer of the Company.  Before joining the Company in this position in May 2015, Mr. Mey served as Executive Vice President and Chief Financial Officer of Atwood Oceanics, Inc. from January 2015 to May 2015, prior to which he served as Senior Vice President and Chief Financial Officer from August 2010.  Mr. Mey was director of Transocean Partners LLC from June 2015 until December 2016.  He served as Director, Senior Vice President and Chief Financial Officer of Scorpion Offshore Ltd. from August 2005 to July 2010.  Prior to 2005, Mr. Mey held various senior financial and other roles in the drilling and financial services industries, including 12 years with Noble Corporation.  He earned an Advanced Diploma in Accounting and a Bachelor of Commerce degree from the University of Port Elizabeth in South Africa in 1985, and he is a chartered accountant.  Additionally, Mr. Mey completed the Harvard Business School Executive Advanced Management Program in 1998.

David Tonnel is Senior Vice President and Corporate Controller of the Company.  Before being named to his current position in April 2017, he served as Senior Vice President, Supply Chain and Corporate Controller from October 2015 to April 2017, as Senior Vice President, Finance and Controller from March 2012 to October 2015 and as Senior Vice President of the Europe and Africa Unit from June 2009 to March 2012.  Mr. Tonnel served as Vice President of Global Supply Chain from November 2008 to June 2009, as Vice President of Integration and Process Improvement from November 2007 to November 2008, and as Vice President and Controller from February 2005 to November 2007.  Prior to February 2005, he served in various financial roles, including Assistant Controller; Finance Manager, Asia Australia Region; and Controller, Nigeria.  Mr. Tonnel joined the Company in 1996 after working for Ernst & Young in France as Senior Auditor.  Mr. Tonnel earned a Master of Science degree in Management from HEC (Hautes Etudes Commerciales) in Paris, France in 1991.