Impairment Losses on Investments
In the fourth quarter of 2013, the Company recorded impairment losses of $99 million, primarily related to the Company's Gladstone equity method investment. The Company determined that losses associated with the investments were other than temporary and accordingly, an impairment loss was recorded. Impairments are discussed in more detail in Item 15 — Note 10, Asset Impairments, to the Consolidated Financial Statements.
Gain on Sale of Equity-Method Investment
In the fourth quarter of 2014, the Company sold its investment in Sabine, as described in Item 15 — Note 3, Business Acquisitions and Dispositions, to the Consolidated Financial Statements. In connection with the sale, the Company received cash proceeds of $35 million and recorded a gain on sale of $18 million.
Loss on Debt Extinguishment
A loss on debt extinguishment of $95 million was recorded for the year ended December 31, 2014, compared to a loss of $50 million in the year ended December 31, 2013. The loss in 2014 was primarily due to the redemption premiums from the redemption of the 2019 Senior Notes. The loss in 2013 included $28 million related to open market repurchases of the 2018 Senior Notes, 2019 Senior Notes and 2020 Senior Notes in the first quarter of 2013. These losses primarily consisted of the premiums paid on redemption and the write-off of previously deferred financing costs. In the second quarter of 2013, a $21 million loss on debt extinguishment was recorded and included $11 million related to the redemption of the 2014 GenOn Senior Notes, which consisted of redemption premiums offset by the write-off of the remaining unamortized premium, and $10 million related to the amendments to the Senior Credit Facility, which consisted primarily of the write-off of previously deferred financing costs.
NRG's interest expense increased by $271 million for the year ended December 31, 2014, compared to the same period in 2013, due to the following:
Increase for issuance of 2022 and 2024 Senior Notes in January and April 2014
Reduction to capitalized interest for projects placed in service
Increase in derivative interest expense primarily for the Alpine interest rate swaps
Increase for the acquisition of EME in April 2014
Increase for the acquisition of Alta Wind in August 2014
Increase for issuance of NRG Yield 2019 Convertible Notes and Senior Notes in February and August 2014
Increase in amortization of premium/discount
Decrease for 7.625% and 8.5% Senior Notes due 2019 redeemed in the first, second and third quarters of 2014
Decrease for 7.625% GenOn Senior Notes due 2014 redeemed in June 2013