This report provides a comparative analysis of the financial sustainability reports of Barclays PLC and AstraZeneca PLC, both listed on the London Stock Exchange. It examines and contrasts their sustainability engagement techniques and strategies, highlighting Barclays' focus on themes like Company, Customer, Colleague, and Society, versus AstraZeneca's emphasis on Access to Healthcare, Environmental Protection, and Ethics. The report further explores the verifiability and assurance of their sustainability reports, noting Barclays' adherence to GRI standards and AstraZeneca's use of multiple external standards, including CDP. The measurement of social and environmental performance is also compared, with Barclays using metrics like Net Promoter Score and AstraZeneca employing the UN Sustainable Development Goals (SDGs). The report concludes by identifying best practices in social/sustainability reporting, emphasizing the importance of materiality, stakeholder engagement, data collection, and external assurance. The report is a contribution from a student to the Desklib platform, a resource for AI-driven study tools.