Operating expenses (excluding depreciation and amortization)
Operating expenses (excluding depreciation and amortization) decreased $13.9 million, or 9%, and $35.5 million, or 8%, during the three and nine months ended September 30, 2019, respectively, as compared to the corresponding periods in 2018. The decreases are primarily attributable to increases in eligible capitalizable costs, receipt of business interruption insurance proceeds, decreases in video and telephony direct expense, and decreases in compensation cost associated with reductions in headcount.
Incremental contribution
Incremental contribution is defined as subscription services revenue less costs directly incurred from third parties in connection with the provision of such services to our customers. Incremental contribution decreased $2.1 million, or 1%, during the three months ended September 30, 2019 compared to the three months ended September 30, 2018 and $2.6 million, or 1%, during the nine months ended September 30, 2019 compared to the nine months ended September 30, 2018. The decreases are primarily due to the decrease in subscription service revenue driven by decreases in Video and Telephony ARPU and RGUs, partially offset by increases in HSD ARPU and RGUs. Direct expenses decreased $2.7 million, or 3%, and $5.5 million, or 2%, during the three and nine months ended September 30, 2019 compared to the corresponding periods in 2018. The decrease is primarily due to decreases in programming expense, which was $88.8 million for the three months ended September 30, 2019 compared to $91.6 million for the three months ended September 30, 2018 and $275.9 million for the nine months ended September 30, 2019 compared to $279.5 million for the nine months ended September 30, 2018.
Selling, general and administrative (SG&A) expenses
Selling, general and administrative expenses increased $3.6 million, or 10%, and $17.3 million, or 15%, during the three and nine months ended September 30, 2019, respectively, compared to the corresponding periods in 2018. The increases are primarily attributable to costs associated with digital transformation initiatives, increases in third party professional fees and sales and marketing expenses, partially offset by decreases in employee stock compensation costs.
Depreciation and amortization expenses
Depreciation and amortization expenses increased $4.6 million, or 10%, and $12.5 million, or 9%, during the three and nine months ended September 30, 2019, respectively, as compared to the corresponding periods in 2018. The increases are primarily attributable to an increase in fixed assets placed into service to rebuild our network infrastructure in the Panama City, FL market which was significantly impacted by Hurricane Michael combined with new financing leases entered into during 2019.
Gain on sale of assets
On December 14, 2017, we sold a portion of our Chicago fiber network to a subsidiary of Verizon for $225.0 million in cash. In addition, we and a subsidiary of Verizon entered into a construction agreement pursuant to which we agreed to complete the build-out of the network in exchange for $50.0 million (which approximated our remaining estimate to complete the network build-out), recognized over time as the remaining network elements were completed and accepted. The Company completed the network build-out as of September 30, 2019. We recognized a $2.5 million loss for the nine months ended September 30, 2019 as a result of the completion and acceptance of such elements during 2019.
Impairment Losses on Intangibles and Goodwill
As a result of the decline in the Company’s common stock price during the three months ended March 31, 2018, we recorded non-cash impairment charges of $143.2 million related to certain franchise operating rights and $73.1 million related to goodwill in certain of our markets. The primary driver of the impairment charges was a decline in the price of our common stock, which reduced market multiples utilized to determine estimated fair market values of