USG recorded $42 million in net income, or $0.30 per diluted share, for the fourth quarter of 2018, compared to a net loss of $69 million, or ($0.49) per diluted share, in the fourth quarter of 2017. The net loss in the fourth quarter of 2017 includes $145 million of income tax expense resulting from the Tax Cuts and Jobs Act. On an adjusted basis, net income of $37 million, or $0.26 per diluted share, for the fourth quarter of 2018 decreased from $77 million, or $0.53 per diluted share, in the fourth quarter of 2017.
USG recorded full year 2018 net sales of $3.3 billion, net income of $196 million, and diluted earnings per share of $1.38 compared to net sales of $3.2 billion, net income of $88 million and diluted earnings per share of $0.60 in 2017. On an adjusted basis, the Company generated full year 2018 net income of $218 million, or diluted earnings per share of $1.51. For comparative purposes, on an adjusted basis, USG recorded net income of $264 million, or diluted earnings per share of $1.80, for the full year of 2017. A full reconciliation of GAAP to adjusted metrics is provided in the attached schedule.
U.S. Wallboard & Surfaces
The U.S. Wallboard & Surfaces segment net sales for the fourth quarter of 2018 decreased $12 million, or 2%, compared with the fourth quarter of 2017. The segment generated $54 million of operating profit in the fourth quarter of 2018 compared to operating profit of $78 million in the fourth quarter of 2017. On an adjusted basis, operating profit of $54 million decreased by $24 million compared to the fourth quarter of 2017. Wallboard volumes decreased 8% compared to the fourth quarter of 2017, outpacing industry volumes by 2%. Wallboard price increased 5% from the fourth quarter of 2017 due primarily to January 2018 and June 2018 price increases. However, wallboard costs were $18 million higher than the prior year quarter primarily due to higher input costs, which were partially offset by $5 million in cost savings in the fourth quarter 2018 due to the Company’s Advanced Manufacturing initiative.
U.S. Performance Materials
The U.S. Performance Materials segment net sales decreased by $1 million, or 1%, compared with the fourth quarter of 2017 due to lower shipments, which was partially offset with higher average realized selling prices. The segment generated $2 million of operating loss in the fourth quarter of 2018 compared to operating profit of $4 million in the fourth quarter of 2017. On an adjusted basis, operating loss of $2 million declined by $6 million compared to the fourth quarter of 2017 primarily due to higher input costs and SG&A investments to accelerate the future adoption of new products.
U.S. Ceilings
The U.S. Ceilings segment net sales decreased $1 million, or 1%, compared to the fourth quarter of 2017. The segment generated $12 million of operating profit in the fourth quarter of 2018 compared to operating profit of $24 million in the fourth quarter of 2017. On an adjusted basis, operating profit of $15 million decreased by $9 million from the fourth quarter of 2017, primarily due to lower volumes and higher costs across tile and grid products, which was partially offset by higher realized average selling prices.
USG Boral
USG Boral net sales decreased $20 million, or 6%, compared to the fourth quarter of 2017. The decrease is primarily due to the unfavorable impact of currency translation of $14 million and lower wallboard shipments. The segment generated $9 million of equity income in the fourth quarter of 2018, which is a $8 million decrease compared to the fourth quarter of 2017 primarily due to a reduction in sales coupled with higher input costs.
Pending Knauf and USG Merger
On June 11, 2018, Gebr. Knauf KG (Knauf) and USG announced that they had entered into a definitive merger agreement pursuant to which Knauf will acquire all the outstanding shares of USG. Under the terms of the merger agreement, USG stockholders will receive $44 per share, which consists of $43.50 per share in cash payable upon