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Item 1.	BUSINESS

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•	residential and nonresidential repair and remodel activity of about 50%,

•	new residential construction of about 35%,

•	new nonresidential construction of about 10%, and

•	other activities, such as exports and temporary construction, of about 5%.

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•	residential and nonresidential repair and remodel activity of about 49%,

•	new residential construction of about 13%,

•	new nonresidential construction of about 33%, and

•	other activity, including exports, of about 5%.

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•	75% of net sales were from repair and remodel activity, primarily nonresidential,

•	20% of net sales were from new nonresidential construction, and

•	5% of net sales were from new residential construction.

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Item 1A.	RISK FACTORS

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Entering into the Merger Agreement to be acquired by Knauf constituted a change of control under the Shareholders Agreement such that, even if the Merger is not completed, or if certain other events of default under the Shareholders Agreement occur with respect to us, we may be required to sell our entire interest in UBBP to Boral at fair market value, as determined in accordance with the Shareholders Agreement. In the event we are forced to sell our interest in UBBP, it may be under terms that we do not consider favorable to us. On August 28, 2018, Boral delivered a default notice under the Shareholders Agreement to commence the process to establish the fair market value of our 50% interest in UBBP. Once fair market value is established, Boral will have the right to purchase our 50% interest in UBBP in accordance with the Shareholders Agreement. Boral’s exercise of its right to purchase our 50% interest in UBBP could occur prior to the closing of the Merger Agreement, in which case we would receive the cash proceeds for our interest, and we would no longer own an interest in UBBP.

•	In the event we are required to sell our interest in UBBP to Boral, we may be restricted from competing in UBBP’s markets for a period of time, many of which we anticipate to be high-growth markets. In addition, in the event we are required to sell our interest in UBBP to Boral, certain of our intellectual property will continue to be licensed to UBBP on an exclusive basis for a period of time.

•

Certain major decisions with respect to UBBP require the majority or unanimous approval of the joint ventures’ boards or shareholders, which could result in a deadlock given the 50/50 ownership and equal board representation structure. Boral may have economic or other business interests or goals that are or become inconsistent with ours, and we may not be able to obtain approval of certain matters that would be in our or UBBP’s best interests. In addition, we may be required to spend additional resources to resolve any dispute with Boral.

•	A deadlock with respect to certain fundamental decisions may result in the triggering of a sale process of UBBP. In such a case, the terms of the sale may be less attractive than if we had held onto our investment.

•	The Shareholders Agreement limits our ability to transfer our interest in UBBP. As a result, we may be unable to sell our interest in UBBP when we would otherwise like.

•

UBBP may not pay dividends if such payments are, among other things, restricted pursuant to the terms of the credit facilities maintained by UBBP, inconsistent with the then-applicable strategic plan, or illegal. Accordingly, we may not receive dividend payments from UBBP in the amounts that we currently anticipate or at all, which may adversely impact our ability to receive any economic benefit from UBBP.

•	In the event Boral is subject to a change of control, or if certain other events of default under the Shareholders Agreement occur with respect to Boral, we will have the right to acquire Boral’s interest in UBBP at fair market value, but it may be on terms that we do not find favorable. In this circumstance, if we do not complete the

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In certain circumstances, a capital call may be issued to the shareholders of UBBP in order to obtain additional funding for the joint ventures' operations. If we do not provide capital and Boral does, Boral may receive additional shares in UBBP, thereby diluting our interest and diminishing our rights under the Shareholders Agreement. Further, although we intend for UBBP to be self-funding, we may nonetheless determine in the future that we need to provide additional capital in order for UBBP to continue operating.

•	Boral may become insolvent, refuse to make additional capital contributions or fail to meet its obligations under the Shareholders Agreement or the two share sale and subscription agreements entered into with Boral, which may result in certain liabilities to us.

•

UBBP has relied in part on new products and technology we have developed. UBBP is contractually entitled to some, but not all, of our new products and recently licensed several new products and technologies from us, including USG Sheetrock® Brand EcoSmart Panels and Ensemble® Acoustical Drywall Ceiling. If UBBP is unable to successfully commercialize on our innovation efforts, the opportunity to grow the joint ventures or for us to deploy our products in UBBP’s territory will be adversely impacted.

•

UBBP is required to protect our licensed trade secrets and confidential intellectual property in its territory, which includes countries where there is a high risk of intellectual property loss, and we also expend significant efforts to secure and enforce our intellectual property rights in UBBP’s territory. If UBBP is not diligent with its protections or our efforts are insufficient and competitors acquire our trade secrets and confidential intellectual property, then there may be a material adverse impact on our business both inside and outside of UBBP’s territory.

•	sensitivity to general economic conditions in each of the countries in which we or UBBP operate, including, in particular, the housing and construction-based markets;

•	compliance with United States laws affecting operations outside of the United States, such as the Foreign Corrupt Practices Act or similar anti-bribery laws and regulations, or corruption in foreign countries;

•	compliance with a variety of local laws and regulations, including environmental and safety laws and regulations;

•	changes in U.S. or foreign tax laws and the interpretation of those laws;

•	imposition of more or new tariffs, quotas, trade barriers, and similar restrictions on our sales outside the United States, including cross-border intercompany sales;

•	fluctuations in currency values and the impact on our consolidated results;

•	changes in foreign currency exchange controls;

•	discriminatory or conflicting fiscal policies;

•	difficulties enforcing intellectual property and contractual rights, and securing information and infrastructure, in certain jurisdictions;

•	greater risk of uncollectible accounts and longer collection cycles; and

•	nationalization of properties by foreign governments.

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Item 1B.	UNRESOLVED STAFF COMMENTS

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Item 3.	LEGAL PROCEEDINGS

Item 4.	MINE SAFETY DISCLOSURES

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Item 5.	MARKET FOR THE REGISTRANT’S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

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Item 6.	SELECTED FINANCIAL DATA

(a)	Results have been adjusted from the originally reported amounts to reflect the adoption of Accounting Standard Update (ASU) 2017-07 which we adopted on January 1, 2018. See Note 2, Recent Accounting Pronouncements, to our consolidated financial statements in Part II, Item 8 of this report.

(b)

Results have been adjusted from the originally reported amounts to reflect L&W, which was sold on October 31, 2016, as a discontinued operation. We recorded a gain of $279 million on the sale of the business. See Note 3, Acquisitions and Dispositions, to our consolidated financial statements in Part II, Item 8 of this report. The Statements of Income results have also been adjusted to reflect the adoption of ASU 2017-07.

(c)	Reflects a charge related to the settlement of the U.S. wallboard pricing class action lawsuits.

(d)	Reflects long–lived asset impairment charges on mining operations in 2016. See Note 12, Long-Lived Asset Impairment Charges, to our consolidated financial statements in Part II, Item 8 of this report. The amount in 2014 reflects impairment charges on manufacturing facilities, capitalized costs for the construction of future facilities and ocean vessels.

(e)	Item relates to our shipping operations, which we exited in 2015.

(f)	Reflects the gain recorded on the sale of our equity method investment in our Knauf-USG joint venture to our 50/50 joint venture partner in 2015 and our share of the net income from the equity method investment for all periods presented.

(g)	Reflects the gain recorded on the deconsolidation and contribution to UBBP of certain of our wholly-owned subsidiaries and consolidated joint ventures.

(h)	Income tax expense for 2018 and 2017 includes a benefit of $11 million and a charge of $145 million, respectively, related to the Tax Cuts and Jobs Act, or the 2017 Tax Act. See Note 14, Income Taxes, to our consolidated financial statements in Part II, Item 8 of this report. The 2015 benefit includes the reversal of a tax valuation allowance of $731 million.

(i)	Excludes currently maturing portion of long-term debt.

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Item 7.	MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

•	Profitably grow our core portfolio,

•	Innovate to address industry challenges,

•	Align and enable our organization, and

•	Maintain disciplined capital allocation.

(a)	Gypsum products include products manufactured and marketed by our U.S. Wallboard and Surfaces segment and Fiberock® brand gypsum fiber panels manufactured and marketed by our U.S. Performance Materials segment.

(b)	Forecast based on the average of the bottom ten and top ten forecasts included in the report, respectively.

(c)	Dodge Data & Analytics' forecast includes several building types which do not generate significant demand for our products.

(d)	The repair and remodel market includes renovation of both residential and nonresidential buildings.

(e)	At the time of the filing of this Form 10-K, December 2018 housing starts were not available from the U.S. Census Bureau.

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(a)	The gypsum board market as determined by the Gypsum Association includes gypsum wallboard, other gypsum-related paneling products, such as glass mat sheathing and gypsum fiber boards, and imports.

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*	Not meaningful

(a)	Results have been adjusted from the originally reported amounts to reflect the adoption of ASU 2017-07 which we adopted on January 1, 2018. See Note 2, Recent Accounting Pronouncements, to our consolidated financial statements in Part II, Item 8 of this report.

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(a)	Results have been adjusted from the originally reported amounts to reflect the adoption of ASU 2017-07 which we adopted on January 1, 2018. See Note 2, Recent Accounting Pronouncements, to our consolidated financial statements in Part II, Item 8 of this report.

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(a)	Results have been adjusted from the originally reported amounts to reflect the adoption of ASU 2017-07 which we adopted on January 1, 2018. See Note 2, Recent Accounting Pronouncements, to our consolidated financial statements in Part II, Item 8 of this report.

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(a)	Results have been adjusted from the originally reported amounts to reflect the adoption of ASU 2017-07 which we adopted on January 1, 2018. See Note 2, Recent Accounting Pronouncements, to our consolidated financial statements in Part II, Item 8 of this report.

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(a)	Results have been adjusted from the originally reported amounts to reflect the adoption of ASU 2017-07 which we adopted on January 1, 2018. See Note 2, Recent Accounting Pronouncements, to our consolidated financial statements in Part II, Item 8 of this report.

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(a)	Operating profit in 2016 included long-lived asset impairment charges of $14 million for Oman and $8 million for China.

(b)	USG share of income from investment accounted for using the equity method in 2016 included long-lived asset impairment charges of $4 million for Oman and $4 million for China.

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(a)	Excludes unamortized deferred issuance costs of $10 million.

(b)	Other long-term liabilities primarily consist of asset retirement obligations that principally extend over a 50-year period. The majority of associated payments are payable toward the latter part of that period.

(c)	Reflects estimated interest payments on debt obligations as of December 31, 2018.

(d)	Purchase obligations primarily consist of contracts to purchase energy, certain raw materials and finished goods.

(e)	Reflects estimates of future spending on active capital projects that were approved prior to December 31, 2018 but were not completed by that date.

(f)	Reflects estimated payments (if required) of gross unrecognized tax benefits.

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Item 7A.	QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

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1.	Significant Accounting Policies

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•	Level 1 – Quoted prices for identical assets and liabilities in active markets;

•	Level 2 – Quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets; and

•	Level 3 – Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.

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2.	Recent Accounting Pronouncements

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(a)	The ten month period ended October 31, 2016 included transaction costs of $8 million.

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(a)	Year ended December 31, 2016 includes long-lived asset impairment charges of $8 million for China and of $14 million for Oman.

(b)	Year ended December 31, 2016 includes long-lived asset impairment charges of $4 million for China and of $4 million for Oman.

(a)	Includes the current portion of long-term debt of $15 million and $16 million as of December 31, 2018 and 2017, respectively.

(b)	Shareholders' equity includes $64 million and $66 million related to non-controlling interests as of December 31, 2018 and 2017, respectively.

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(a)	Principal amounts exclude unamortized debt issuance costs.

(b)

Callable at any time, in whole or in part, prior to the call date at a redemption price equal to 100% of the principal plus a premium (as outlined in the respective indentures), plus any accrued and unpaid interest on the principal amount being called. Callable after the call date at stated redemption prices (as outlined in the applicable indenture), plus any accrued and unpaid interest on the principal amount being called.

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8.	Fair Value Measurements

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(a)	In 2016, $26 million of the settlement charge reflects the increase in lump sum benefits paid largely driven by the sale of L&W and $9 million reflected payments from our supplemental plan.

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(a)	Certain investments in commingled/pooled equity funds have been classified as Level 2 because observable quoted prices for these institutional funds are not available.

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10.	Share-Based Compensation

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(a)	Other miscellaneous sales primarily includes shipping and handling costs billed to customers.

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(a)

In 2017, we recorded the impact of the 2017 Tax Act which included the transition tax on deferred foreign earnings, net of foreign tax credits, of $9 million, an increase in the valuation allowance related to foreign tax credits of $106 million, an increase in the valuation allowance of our state NOLs due to the change in federal benefit related to those assets of $18 million, anticipated sequestration of our AMT credits of $3 million and the impact of the corporate rate change on deferred tax assets and liabilities of $9 million. In 2018, we reversed $2 million of anticipated sequestration of our AMT credits based upon guidance released by the OMB and had a decrease in the valuation allowance of $9 million related to anticipated future realization of foreign tax credits.

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(a)	The sum of the four quarters is not necessarily the same as the total for the year.

(b)	Income from continuing operations and net income included a loss on extinguishment of debt of $22 million for the second quarter of 2017 and income tax expense of $145 million related to the 2017 Tax Act for the fourth quarter of 2017. See Notes 6, Debt, and 14, Income Taxes, respectively.

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(a)	Reflects receivables written off as related to doubtful accounts, cash discounts allowed and reductions in the income tax valuation allowance.

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Item 9.	CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

Item 9A.	CONTROLS AND PROCEDURES

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Item 9B.	OTHER INFORMATION

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Item 10.	DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE

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*	Chairperson

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Item 11.	EXECUTIVE COMPENSATION

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(a)	Straight-line interpolation is used to determine values between performance thresholds.

(b)

Because Mr. Salah has more direct profit and loss accountability for the performance of the business units in his division, 25% of his annual incentive award opportunity for 2018 was based on the achievement of the corporate adjusted net earnings goal set by the Committee and 25% was based on the achievement of the adjusted operating profit goal set by the Committee for his division, as described further below.

(c)

For 2018, GAAP net earnings were $196 million and were adjusted to exclude expenses related to the Merger, gain and loss on disposition of assets, a charge for a legal judgment on a contract dispute from 2004, a charge for the termination of a marketing contract, the impact of accounting changes, earnings from discontinued operations, costs associated with the integration of Ceilings Plus and divisional realignment, and changes in tax law. Net earnings were also neutralized for foreign currency and incentive plan expense above or below planned amounts. These adjustments had no impact on the payout percentage, which remained at 0% even after the adjustments.

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(a)

Consolidated operating margin (consolidated operating profit divided by consolidated net sales) was 6.8% in 2018. To calculate adjusted operating margin, operating profit was adjusted to include equity income from UBBP and exclude expenses related to the Merger, gain on disposition of assets, a charge for a legal judgment on a contract dispute from 2004, a charge for the termination of a marketing contract, the impact of accounting changes and costs associated with the integration of Ceilings Plus and divisional realignment costs, and was neutralized for foreign currency and incentive plan expense above or below planned amounts. Net sales were adjusted to exclude the impact of accounting changes, including those associated with the integration of Ceilings Plus and were neutralized for foreign currency. These adjustments had no impact on the payout percentage, which remained at 0% even after the adjustments.

(b)

Net income attributable to UBBP was $84 million in 2018. To calculate UBBP adjusted EBIT, net income attributable to UBBP was adjusted to exclude net interest, taxes on income, and net income attributable to non-controlling interest, and was neutralized for foreign currency and incentive plan expense above or below planned amounts. These adjustments had no impact on the payout percentage, which remained at 0% even after the adjustments.

(c)

U.S. Wallboard and Surfaces operating profit was $248 million in 2018. To calculate adjusted operating profit, operating profit was adjusted to exclude a gain on disposition of assets and the impact of accounting changes and was neutralized for selling and administrative expenses allocation and incentive plan expense above or below planned amounts. These adjustments had no impact on the payout percentage, which remained at 0% even after the adjustments.

(d)	Canada and Mexico combined operating profit was $36.2 million in 2018. To calculate adjusted operating profit, operating profit was adjusted to exclude the impact of accounting changes and was neutralized for foreign currency and incentive plan expense above or below planned amounts.

(e)	We do not publicly disclose U.S. Wallboard gross margin or U.S. Surfaces gross margin because that information constitutes confidential commercial and financial information, the disclosure of which would cause us competitive harm. The target levels for these Focus Targets were set at challenging, but achievable, levels.

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(a)	Straight-line interpolation is used to determine values between performance thresholds.

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(a)	Straight-line interpolation is used to determine values between vesting tiers.

(a)	Straight-line interpolation is used to determine values between performance thresholds.

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(a)

The amounts shown in this column reflect the aggregate grant date fair values computed in accordance with FASB ASC Topic 718 for MSUs and performance shares granted under our LTIP. However, for purposes of this table, estimates of forfeitures have been removed. A Monte Carlo simulation has been chosen for both the MSU and performance share valuations. The assumptions used in valuing the MSUs and performance shares are described in Note 10, Share-Based Compensation, to our consolidated financial statements in Part II, Item 8 of this report. Expense is recognized over the requisite service period (the period from the grant date to the end of the performance or vesting period). Awards under the LTIP are described further in Item 11, Executive Compensation - Compensation Discussion and Analysis - Long-Term Incentive.

(b)	The amounts shown in this column include payments under our annual MIP for services performed in the year indicated.

(c)

The amounts in this column reflect the aggregate change in the actuarial present value of accumulated benefits under our defined benefit pension plans from December 31, 2017 through December 31, 2018, the plan measurement dates used for financial statement reporting purposes. The named executive officers had no above-market or preferential earnings on deferred compensation. No amount is reflected in this column for Mr. Dannessa for 2018 because the aggregate change in the actuarial present value of his accumulated benefit in such year was negative $286,049.

(d)

The amounts in this column reflect all other compensation for 2018 that could not properly be reported in any other column. Details regarding all other compensation components are provided in the supplemental table below. Several of the benefits listed in the table result in imputed income to the named executive officer. In the case of company-provided automobiles, the amounts shown reflect the portion of our cost attributed to personal use of the vehicle by the named executive officer, including the cost of lease payments, fuel, insurance, license and title, maintenance and repairs, less any gain we realized upon sale of the vehicle. All other items are valued at full actual cost. We also provide additional executive death and disability benefit coverage to our executive officers on a self-insured basis. There is a small incremental cost to us for providing this additional coverage. From time to time, executive officers may use our tickets to sporting venues for personal use. We believe there is no incremental cost associated with our executive officers using our tickets to sporting venues for personal use because the tickets are purchased in advance for the entire season with the intention that they be used for business purposes, they cannot be returned for a refund if they are unused and use for personal purposes occurs only if the tickets have not been reserved for use for a business purpose. No value is attributed in the 2018 Summary Compensation Table to personal benefits for which we incur no incremental cost. The amounts in this column do not include the Dividend-Make Whole Amounts, which have not yet been paid.

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(a)	The gain we realized upon sale of the vehicle exceeded the cost of lease payments, fuel, insurance, license and title, maintenance and repairs.

(a)	The grant date is the date on which the equity awards were ratified by our Board.

(b)

The amounts in the Target column reflect the target amounts payable under the 2018 MIP. The 2018 MIP is described in Item 11, Executive Compensation - Compensation Discussion and Analysis - Annual Incentive. There was no threshold-level payout under the 2018 MIP. The maximum payout under the 2018 MIP was 200% of target. Total payments to any one individual under the 2018 MIP may not exceed $4 million.

(c)

MSUs were granted to each named executive officer under our LTIP. The amount of common stock to be issued in respect of the MSUs can range from zero to 150% of target based on the percentage change in the price of our common stock over the applicable vesting period. The MSUs will generally be earned on December 31, 2020, with a 10% appreciation in the Market Value (as defined above in the Compensation Discussion and Analysis) of our common stock required for vesting of the target number of shares of common stock. With respect to the MSUs, the amounts in the Threshold column reflect the amount of common stock to be awarded upon a 50% decrease in Market Value, the Target column reflects the amount of common stock to be awarded upon achievement of a 10% appreciation in the Market

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(d)

Performance shares were granted to each named executive officer under our LTIP. The number of performance shares earned will vary from zero to 200% of target based on our total stockholder return relative to the total stockholder return of the companies in the Dow Jones U.S. Construction and Materials Index, or the Index, for the performance period, with the Index adjusted to reflect changes in the companies included in the Index for the performance period. The performance shares will generally be earned on December 31, 2020. With respect to the performance shares, the amounts in the Target column reflect the number awarded to the named executive officers on the grant date. The amounts in the Threshold column reflect the number of performance shares that will vest if our total stockholder return is at the 35th percentile of the total stockholder return of the Index companies, and the amounts in the Maximum column reflect the number of performance shares that will vest if our total stockholder return is at or above the 90th percentile of the total stockholder return of those companies. Vesting will be pro-rated based on the number of full months employed during the performance period in the case of death, disability or retirement, and pro-rated awards will be paid at the end of the three-year-performance period. The Merger Agreement provides that performance shares that are outstanding immediately prior to the effective time of the Merger will become fully vested and will be converted into the right to receive a cash payment equal to the product of (i) the number of shares of our common stock earned under such performance share, determined by substituting the closing consideration for the ending stock price in determining the achievement of the performance goal measured as of the effective time of the Merger, multiplied by (ii) the closing consideration, provided that to the extent any such performance shares constitute nonqualified deferred compensation subject to Section 409A of the Code, such cash payment will be paid in accordance with the applicable award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. Any performance shares not earned as of the effective date of the Merger will be forfeited.

(e)

The amounts in this column reflect the aggregate grant date fair value of the equity awards granted computed in accordance with FASB ASC Topic 718, and exclude the effect of estimated forfeitures. The assumptions used in valuing the MSUs and performance shares are described in Note 10, Share-Based Compensation, to our consolidated financial statements in Part II, Item 8 of this report. We did not grant any stock options in 2018.

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(a)

The outstanding RSUs awarded to Ms. Scanlon in 2015 and 2016 will vest on September 1, 2019 and November 1, 2020, respectively. The outstanding RSUs awarded to Mr. Dannessa in 2015 will vest on September 1, 2019. The outstanding RSUs awarded to Mr. Salah in 2015 and 2017 vest on August 3, 2019 and October 2, 2020, respectively. The outstanding RSUs awarded to Ms. Warner in 2016 and 2017 will vest on January 4, 2020 and February 8, 2020, respectively.

(b)	The amounts in this column represent the number of RSUs indicated in the “Number of Shares or Units of Stock That Have Not Vested” column multiplied by the closing price of our common stock on December 31, 2018.

(c)

With respect to the MSUs awarded in 2017 and 2018, the number of MSUs reflected in this column is the number of shares that would be earned if the maximum and target level of performance, respectively, is achieved, as performance with respect to those shares is tracking between the target and maximum levels for 2017 and between the threshold and target levels for 2018. The MSUs awarded in 2017 and 2018 will generally be earned on December 31, 2019 and December 31, 2020, respectively, with a 10% appreciation in the Market Value of our common stock required for vesting of the target number of shares. The amount of MSUs ultimately awarded may range from zero to 150% of the target. With respect to the performance shares awarded in 2017 and 2018, the number of performance shares reflected in this column is the number of shares that would be earned if the maximum level of performance (200% of target) is achieved, as performance with respect to those shares is tracking between the intermediate and maximum levels for 2017 and 2018. To the extent the performance criteria is met, the performance shares awarded in 2017 and 2018 will be earned on December 31, 2019 and December 31, 2020, respectively. The number of performance shares earned will vary from zero to 200% of target.

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(d)

The amounts in this column represent the number of MSUs or performance shares indicated in the “Equity Incentive Plan Awards: Number of Unearned Shares, Units or Other Rights That Have Not Vested” column multiplied by the closing price of our common stock on December 31, 2018. In addition to, and not included in, these amounts are the Dividend Make-Whole Amounts that relate to MSUs and performance shares in the following amounts, estimated assuming the effective time of the Merger was December 31, 2018: Ms. Scanlon - $219,496, Mr. Hilzinger - $124,636, Mr. Dannessa - $66,912, Mr. Salah - $56,343, Ms. Warner - $61,171.

(a)	The amount in this column represents the difference between the aggregate market value of the shares of our common stock subject to the option on the exercise date and the aggregate exercise price of the option.

(b)	The amounts in this column represent the aggregate market value of the shares of our common stock acquired on the dates the RSUs, performance shares and MSUs vested.

•	December 31, 2018 measurement date: 4.31% for the Retirement Plan and 4.08% for the Supplemental Retirement Plan; and

•	December 31, 2017 measurement date: 3.63% for the Retirement Plan and 3.39% for the Supplemental Retirement Plan.

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(a)	Represents the number of years and months of service credited to the named executive officer under the Plans, computed as of December 31, 2018, the pension plan measurement date used for financial statement reporting purposes with respect to our audited financial statements for 2018.

(b)	Computed as of December 31, 2018, the pension plan measurement date used for financial statement reporting purposes with respect to our audited financial statements for 2018.

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(a)	This amount is not reported in the Summary Compensation Table.

(b)	Of this amount, $77,366 was previously reported as non-equity incentive plan compensation in the Summary Compensation Table.

•	2018 MIP awards;

•	performance shares earned as of the end of 2018;

•	MSUs earned as of the end of 2018;

•	balances under the USG Corporation Investment Plan and USG Corporation Deferred Compensation Plan;

•	vested pension benefits under the USG Corporation Retirement Plan and USG Corporation Supplemental Retirement Plan;

•	retiree medical benefits; and

•	death benefits under our Executive Death Benefit Plan.

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•	“Change in Control” generally includes (i) the acquisition of 20% of the voting power of our common stock, (ii) a change in a majority of the members of our Board, (iii) the consummation of a reorganization, merger or consolidation, or sale of all or substantially all of our assets or (iv) stockholder approval of a complete liquidation of USG;

•	“Cause” generally includes the executive’s (i) conviction of a crime in connection with the executive’s duties with USG, (ii) intentionally damaging our property or (iii) intentionally disclosing our confidential information; and

•	“Good Reason” generally includes (i) a material diminution in the executive’s duties and responsibilities, (ii) a reduction in the executive’s base salary, target incentive opportunities or benefits or (iii) a required relocation.

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(a)	The amounts in this row include the accelerated and unaccelerated 2016 performance shares. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

(b)	The amounts in this row include the accelerated and unaccelerated 2016 MSUs. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

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(a)	The amounts in this row include the accelerated and unaccelerated 2016 performance shares. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

(b)	The amounts in this row include the accelerated and unaccelerated 2016 MSUs. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

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(a)	The amounts in this row include the accelerated and unaccelerated 2016 performance shares. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

(b)	The amounts in this row include the accelerated and unaccelerated 2016 MSUs. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

(a)	The amounts in this row include the accelerated and unaccelerated 2016 performance shares. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

(b)	The amounts in this row include the accelerated and unaccelerated 2016 MSUs. For further information see Compensation Discussion and Analysis - Elements of Total Compensation - Long-Term Incentive - Merger-Related Compensation Actions - 280G Acceleration of 2016 Awards.

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(a)

Mr. Lavin deferred his annual cash retainer into 2,236.9728 deferred stock units, Mr. Leer deferred 5% of his annual cash retainer into 253.1311 deferred stock units, and Messrs. Burke, Carter, Hernandez, Lavin and Leer each deferred his annual stock grant into 2,807.3459 deferred stock units, in each case pursuant to the terms of our Director Compensation Program. Directors hold the number of deferred stock units shown in the Security Ownership of Directors and Executive Officers table in Item 12, Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters. A portion of the total deferred stock units held are classified as liability awards for accounting purposes because the director can elect to receive payment in shares of common stock or cash. The remainder are classified as equity awards. The balances of liability awards are adjusted over the course of the year to reflect changes in the market value of our stock. The net impact of this accounting treatment in 2018 was to increase the award balance for Mr. Hernandez by $110,000.

(b)

Each of Ms. Haggerty and Messrs. Armario and Kenney received his or her annual stock grant in shares of our common stock. They were each issued 2,808 shares based on the average of the high and low sales prices of a share of our common stock on December 31, 2018. The amounts in this column for Ms. Haggerty and Messrs. Armario and Kenney reflect the aggregate grant date fair value of the shares issued to them.

(c)

Reflects matching contributions under the USG Foundation matching gift program. This program is generally available to our U.S. employees and to our directors. The USG Foundation matches up to 50% of donations made to eligible charitable organizations up to a maximum of $2,500 in matches per year for each individual. The amounts shown include matches for gifts that were made in 2017 but, due to administrative processing time, were paid by the USG Foundation in 2018.

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Item 12.	SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS

(a)

Equity compensation plans not approved by stockholders includes an aggregate of 229,779 fully vested deferred stock units granted to our non-employee directors that are payable in shares of common stock and 23,948 fully vested deferred stock units granted to our non-employee directors that are payable in cash or shares of common stock, at such director’s option.  The deferred stock units increase or decrease in value in direct proportion to the market value of our common stock and will be paid following termination of service as a director. Amount does not include an aggregate of 618 fully vested deferred stock units granted to our non-employee directors that must be settled in cash. See Note 10, Share-Based Compensation, to our consolidated financial statements in Part II, Item 8 of this report for additional information regarding the impact of the Merger.

(b)	Weighted-average exercise price calculation for equity compensation plans not approved by stockholders does not reflect the inclusion of fully-vested deferred stock units granted to our non-employee directors because that type of award does not have an exercise feature.

(a)	Unless otherwise noted, each individual or member of the group has sole voting power and investment power with respect to the shares shown in this column.

(b)

Indicates the non-voting deferred stock units credited to the account of the individual director or members of the group under current and past director compensation programs. The units increase or decrease in value in direct proportion to the market value of our common stock and are paid in shares of common stock following termination of Board service. However, as described in Item 11, Executive Compensation - 2018 Director Compensation, one director elected to continue the option to receive cash or shares of common stock for deferred stock

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(c)	As of January 31, 2019, neither any director nor executive officer, nor our directors and executive officers as a group, beneficially owned more than 1% of our outstanding common stock.

(d)	Includes 2,619 shares held by trusts for the benefit of Mr. Armario’s children.

(e)	Includes 36,175 shares held by M&S Hilzinger Family, LP, over which Mr. Hilzinger and his wife share voting and investment power.

(f)	Includes 3,000 shares held by the Sloan D. Salah Trust, over which Mr. Salah and his wife share voting and investment power.

(a)

The number of shares of our common stock shown as beneficially owned includes (a) 39,002,016 shares of our common stock held by National Indemnity Company, a Nebraska insurance corporation (“NICO”), which is an indirect subsidiary of Berkshire Hathaway, Inc., a Delaware corporation (“Berkshire Hathaway”), (b) 14,035,088 shares of our common stock (the “BH Nebraska Shares”) held by Berkshire Hathaway Life Insurance Company of Nebraska, a Nebraska corporation (“BH Nebraska”), (c) 7,894,736 shares of our common stock (the “BH Assurance Shares,” and together with the BH Nebraska Shares, the “Nebraska/Assurance Shares”) held by Berkshire Hathaway Assurance Corporation, a New York corporation (“BH Assurance”), and (d) 4,385,964 shares of our common stock (the “General Re Life Shares”) held by General Re Life Corporation, a Connecticut corporation (“General Re Life”). Mr. Buffett, Chairman of the Board of Directors of Berkshire Hathaway, may be deemed to control Berkshire Hathaway, which controls BH Nebraska, BH Assurance and General Re Life. Thus, both Mr. Buffett and Berkshire Hathaway may be considered to have beneficial ownership of the Nebraska/Assurance Shares and the General Re Life Shares. NICO, a direct subsidiary of Berkshire Hathaway and the direct parent company of BH Nebraska and BH Assurance, also may be considered to have beneficial ownership of the Nebraska/Assurance Shares. General Reinsurance Corporation, a Delaware corporation (“General Reinsurance”), an indirect subsidiary of Berkshire Hathaway and the direct parent company of General Re Life, also may be considered to have beneficial ownership of the General Re Life Shares. General Re Corporation, a Delaware corporation (“General Re”), a direct subsidiary of Berkshire Hathaway and the direct parent company of General Reinsurance, also may be considered to have beneficial ownership of the General Re Life Shares. BH Nebraska has voting and investment power with respect to the BH Nebraska Shares. BH Assurance has voting and investment power with respect to the BH Assurance Shares. However, Mr. Buffett, who may be deemed to control BH Nebraska and BH Assurance, directs the investment of BH Nebraska and BH Assurance. Thus, Mr. Buffett, Berkshire Hathaway, and NICO share voting and investment power with respect to the Nebraska/Assurance Shares. General Re Life has voting and investment power with respect to General Re Life Shares. However, Mr. Buffett, who may be deemed to control General Re Life, directs the investment of General Re Life. Thus, Mr. Buffett, Berkshire Hathaway, General Reinsurance and General Re share voting and investment power with respect to the General Re Life Shares.

(b)

C & G Verwaltungs GmbH, a limited liability company organized under the laws of the Federal Republic of Germany (“C&G”), is an indirect subsidiary of Knauf controlled by members of the Knauf family. Martin Stürmer and Jörg Schanow are the general managers of C&G, and Alexander Knauf and Manfred Grundke are the general partners of Knauf. C&G and Knauf both report that they have sole voting and dispositive power with respect to 14,757,258 shares of our common stock. On June 11, 2018, Knauf filed a Schedule 13D to report entry by Knauf and Merger Sub into a voting agreement, dated June 10, 2018, with Berkshire Hathaway, in which Berkshire Hathaway agreed, among other things and subject to the terms thereof, to vote (or cause to be voted) all shares of our common stock then beneficially owned by Berkshire Hathaway, directly or indirectly, for adoption of the Merger Agreement and approval of the Merger and the other transactions contemplated thereby and against any competing acquisition proposals relating to USG, which could impact the number of shares that Knauf could be deemed to beneficially own. In Knauf’s June 11, 2018 Schedule 13D, Knauf disclaims that it constitutes a “group” (within the meaning of Section 13(d)(3) of the Exchange Act) with Berkshire Hathaway and, pursuant to Rule 13d-4 under the Exchange Act, disclaims beneficial ownership of any shares of our common stock beneficially owned by Berkshire Hathaway or any of its affiliates.

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(c)

Based on information provided in a Schedule 13G filed with the SEC on February 12, 2019 by The Vanguard Group, Inc., an investment adviser (“Vanguard”). Vanguard reported that it has sole power to vote 40,054 shares, shared power to vote 11,046 shares, sole power to dispose of or to direct the disposition of 7,330,422 shares and shared power to dispose of or to direct the disposition of 42,605 shares. Each of Vanguard Fiduciary Trust Company (“Vanguard Trust”) and Vanguard Investments Australia, Ltd. (“Vanguard Investments”) are wholly owned subsidiaries of Vanguard. Vanguard Trust is the beneficial owner of 31,559 shares, as a result of its serving as investment manager of collective trust accounts, and Vanguard Investments is the beneficial owner of 19,541 shares, as a result of its serving as investment manager of Australian investment offerings.

Item 13.	CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE

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•	Mr. Carter is a director of NRG Energy, Inc., from which we purchase electrical power and synthetic gypsum, and receive payments from in connection with an energy demand response program.

•	Ms. Haggerty is a director of Johnson Controls International plc, from which we purchase building efficiency services, and her brother is a partner at a firm used by us for financial valuation services.

•	Mr. Hernandez is a director of Albemarle Corporation, from which we purchase industrial batteries.

•	Mr. Kenney is an executive officer and a director of GATX Corporation, from which we lease railcars.

•	Mr. Lavin is a director of ITT Inc., from which we purchase equipment.

•	Mr. Leer is a director of Norfolk Southern Corporation, from which we purchase rail transportation services, and Ms. Scanlon also serves on the Norfolk Southern board. Mr. Leer is also a director of Parsons Corporation, from which we purchase construction contractor labor.

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Item 14.	PRINCIPAL ACCOUNTING FEES AND SERVICES

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Item 15.	EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

(a)	1 and 2. See Part II, Item 8, Financial Statements and Supplementary Data, for an index of our consolidated financial statements and supplementary data schedule.

(b)	The information in the Exhibit Index of this annual report on Form 10-K is incorporated into this Item 15(b) by reference.

Item 16.	FORM 10-K SUMMARY

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*	Management contract or compensatory plan or arrangement

**	Filed or furnished herewith

†	Schedules and other similar attachments have been omitted pursuant to Item 601(b)(2) of Regulation S-K. The registrant hereby undertakes to furnish supplementally copies of any of the omitted schedules and other similar attachments upon request by the SEC, provided that the registrant may request confidential treatment for any schedule or other similar attachment so furnished.

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