Revenue from our IP Optical Networks segment was $82.2 million and $87.4 million in the three months ended September 30, 2024 and 2023, respectively. Gross profit and gross margin for this segment were $25.3 million and 30.8%, respectively, in the three months ended September 30, 2024, and $28.8 million and 32.9%, respectively, in the three months ended September 30, 2023. Revenue from our IP Optical Networks segment was $242.2 million and $244.4 million in the nine months ended September 30, 2024 and 2023, respectively. Gross profit and gross margin for this segment were $80.2 million and 33.1%, respectively, in the nine months ended September 30, 2024, and $66.2 million and 27.1%, respectively, in the nine months ended September 30, 2023.
Our operating expenses were $110.5 million and $102.6 million in the three months ended September 30, 2024 and 2023, respectively, and $315.8 million and $327.3 million in the nine months ended September 30, 2024 and 2023, respectively. The increased operating expenses in the three months ended September 30, 2024 compared to 2023 are primarily related to a $5.0 million legal settlement and associated legal fees related to certain specific legal matters. Operating expenses for the three months ended September 30, 2024 included $6.5 million of amortization of acquired intangible assets, and $3.8 million of restructuring and related expense. Operating expenses for the three months ended September 30, 2023 included $7.2 million of amortization of acquired intangible assets, $0.8 million of acquisition-, disposal- and integration-related expense, and $2.7 million of restructuring and related expense. The decreased operating expenses in the nine months ended September 30, 2024 compared to 2023 are primarily related to lower restructuring and related expense, acquisition-, disposal- and integration-related expense and amortization of acquired intangible assets. Operating expenses for the nine months ended September 30, 2024 included $19.7 million of amortization of acquired intangible assets, and $8.8 million of restructuring and related expense. Operating expenses for the nine months ended September 30, 2023 included $21.7 million of amortization of acquired intangible assets, $3.0 million of acquisition-, disposal- and integration-related expense, and $13.9 million of restructuring and related expense.
We recorded stock-based compensation expense of $4.0 million and $5.0 million in the three months ended September 30, 2024 and 2023, respectively, and $12.1 million and $16.9 million in the nine months ended September 30, 2024 and 2023, respectively. These amounts are included as components of both Cost of revenue and Operating expenses in our condensed consolidated statements of operations.
See "Results of Operations" in this MD&A for a discussion of the changes in our revenue and expenses for three and nine months ended September 30, 2024 compared to three and nine months ended September 30, 2023.
Restructuring and Cost Reduction Initiatives
Our CODM approved workforce reductions in 2024 for certain of our operating locations to correspond with the current sales levels in those areas. We recorded $2.2 million in the three months ended September 30, 2024 related to these actions.
In February 2023, our Board of Directors approved a strategic restructuring program (the "2023 Restructuring Plan") to streamline our operations in order to support our investment in critical growth areas. The 2023 Restructuring Plan includes, among other things, charges related to a workforce reduction. Any potential positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with the 2023 Restructuring Plan, we recorded restructuring and related expense for severance related costs of $0.1 million and $2.1 million in the three and nine months ended September 30, 2024, respectively, and $0.9 million and $9.4 million in three and nine months ended September 30, 2023, respectively. We anticipate that we will record nominal future expense for severance in connection with the 2023 Restructuring Plan.
In February 2022, our Board of Directors approved a strategic restructuring program (the "2022 Restructuring Plan") to streamline our operations in order to support our investment in critical growth areas. The 2022 Restructuring Plan includes, among other things, charges related to a consolidation of facilities and a workforce reduction. Any positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with the 2022 Restructuring Plan, we recorded restructuring and related expense of $1.5 million and $4.5 million in the three and nine months ended September 30, 2024, respectively, for variable and other facilities-related costs, and we recorded restructuring and related expense of $1.9 million and $4.6 million in the three and nine months ended September 30, 2023, respectively. The amount for the three months ended September 30, 2023 was