($18.78) per share, as well as stock-based compensation expense of $51.0 million, or ($0.32) per share, and amortization of acquired intangibles of $49.1 million, or ($0.30) per share.
Results for the second quarter of 2021 included stock-based compensation expense of $83.0 million, or ($0.53) per share, amortization of acquired intangibles of $46.1 million, or ($0.30) per share, loss on extinguishment of debt $31.4 million, or ($0.20) per share, and non-cash income taxes charges of $3.2 million, or ($0.02) per share.
Adjusted EBITDA* decreased 30% to $46.7 million, compared to $66.8 million for the second quarter of 2021.
GAAP gross margin, which includes depreciation and amortization, was 68.2 percent for the second quarter of 2022, compared to 67.9 percent for the second quarter of 2021.
Adjusted gross margin* was 69.2 percent for the second quarter of 2022, compared to 68.1 percent for the second quarter of 2021.
Average revenue per U.S. paid member increased to $2.60 in the second quarter of 2022, from $2.31 in the second quarter of 2021.
Six Months Ended June 30, 2022
Revenue increased 21% to $1,157.7 million from $956.8 million in the first half of 2021. Access fees revenue grew 24% to $1,010.1 million, and visit fee revenue grew 10% to $134.7 million. U.S. Revenues grew 21% to $1,012.6 million, and International revenues grew 20% to $145.1 million for the first half of 2022.
Non-cash goodwill impairment charges of $9.6 billion were recorded in the first half of 2022. The non-cash charges had no impact on the provision for income taxes.
Net loss totaled $9,776.0 million, or ($60.72) per share, for the first half of 2022, compared to $333.5 million, or ($2.16) per share, for the first half of 2021. Results for the first half of 2022 primarily included non-cash goodwill impairment charges of $9,630.0 million, or ($59.81) per share, as well as stock-based compensation expense of $111.4 million, or ($0.69) per share, and amortization of acquired intangibles of $98.5 million, or ($0.61) per share.
Results for the first half of 2021 included stock-based compensation expense of $169.3 million, or ($1.10) per share, amortization of acquired intangibles of $90.9 million, or ($0.59) per share, loss on extinguishment of debt $42.9 million, or ($0.28) per share, and non-cash income taxes charges of $90.2 million, or ($0.59) per share.
Adjusted EBITDA* decreased 18% to $101.2 million compared to $123.4 million for the first half of 2021.
GAAP gross margin, which includes depreciation and amortization, was 67.1 percent for the first half of 2022, compared to 67.4 percent for the first half of 2021.
Adjusted gross margin* was flat at 68.1 percent for the first half of 2022 and 2021.
Average revenue per U.S. paid member increased to $2.56 in the first half of 2022, from $2.20 in the first half of 2021.