Meeting pledged climate goals requires substantial investments in renewable energy sources. At the same time, the global economy faces significant risks from stranded fossil fuel assets. Research shows that most fossil fuel companies remain misaligned with climate targets, making only minimal portfolio adjustments. Although integrated assessment models (IAMs) are widely used to model the energy transition, they primarily operate at the country or regional level, lacking the details needed to capture firm-specific technology portfolios and financial constraints. We introduce a firm-level modeling approach that evaluates the impacts of IAM scenarios to corporate asset portfolios, enabling a more detailed assessment of transition risks. By incorporating firm-level data, our approach provides a more realistic representation of how existing assets evolve under different climate scenarios.