Integrated Yield Ramp revenue decreased $3.7 million for the nine months ended September 30, 2024, compared to the nine months ended September 30, 2023, primarily due to lower hours worked on fixed-fees engagements and Gainshare from decreased customer wafer shipments at non-leading-edge nodes.
Our Integrated Yield Ramp revenue may continue to fluctuate from period to period primarily due to the contribution of Gainshare, which is dependent on many factors that are outside our control, including among others, continued production of ICs by our customers at facilities at which we generate Gainshare, sustained yield improvements by our customers, and whether we enter into new contracts containing Gainshare.
Our Analytics and Integrated Yield Ramp revenues may also fluctuate in the future and are dependent on a number of factors, including the semiconductor industry’s continued acceptance of our products, services and solutions, the timing of purchases by existing and new customers, cancellations by existing customers, and our ability to attract new customers and penetrate new markets, supply chain challenges and further penetration of our current customer base. Fluctuations in future results may also occur if any of our significant customers renegotiate pre-existing contractual commitments, including due to adverse changes in their own business.
Costs of Revenues
Costs of revenues consist primarily of costs incurred to provide and support our services, costs recognized in connection with licensing our software, IT and facilities-related costs and amortization of acquired technology. Service costs include material costs, hardware costs (including cost of leased assets under sales-type lease), personnel-related costs (including compensation, employee benefits, bonus and stock-based compensation expense), subcontractor costs, overhead costs, travel expenses, and allocated facilities-related costs. Software license costs consist of costs associated with third-party cloud-delivery related expenses and licensing third-party software used by us in providing services to our customers in solution engagements or sold in conjunction with our software products.
The decrease in costs of revenues of $1.8 million for the three months ended September 30, 2024, compared to the three months ended September 30, 2023, was primarily due to (i) a $2.0 million decrease in hardware costs and (ii) a $0.5 million decrease in facilities and IT-related costs including depreciation and amortization expense. These decreases were partially offset by (a) a $0.3 million increase in subcontractor costs, (b) a $0.3 million increase in third-party cloud-delivery costs, and (c) a $0.2 million increase in personnel-related costs mostly resulting from higher stock-based compensation expenses.
The decrease in costs of revenues of $0.3 million for the nine months ended September 30, 2024, compared to the nine months ended September 30, 2023, was primarily due to (i) a $0.8 million decrease in facilities and IT-related costs including depreciation and amortization expense, and (ii) a $0.6 million decrease in hardware costs. These decreases were partially offset by (a) a $0.5 million increase in third-party cloud-delivery costs, (b) a $0.4 million increase in subcontractor costs, and (c) a $0.2 million increase in personnel-related costs mostly resulting from higher stock-based compensation expenses, higher other compensation expenses (including employee benefit costs), increased headcount, and worldwide salary increases, partially offset by lower bonus expense.
Gross Margin
Gross margin increased seven percentage points for the three months ended September 30, 2024, to 73%, compared to 66% for the three months ended September 30, 2023. The higher gross margin during the three months ended September 30, 2024, was primarily due to higher Analytics revenue and lower cost of revenues for the three months ended September 30, 2024.
Gross margin increased one percentage point for the nine months ended September 30, 2024, to 70%, compared to 69% for the nine months ended September 30, 2023. The higher gross margin during the nine months