The service best suited for this task is Amazon QuickSight. It is a fully managed business intelligence service that enables the creation of interactive visualizations and dashboards. As it is serverless, it does not require provisioning or managing infrastructure, aligning with the financial institution's needs. It can connect directly to a relational database, facilitating real-time data reporting with minimal effort. The three incorrect options, while valuable in their domains, do not specialize in visualization. Athena is for SQL querying of data in S3, EMR is a big data processing service, and Glue is intended for serverless ETL workloads, none of which intrinsically offer dashboarding or reporting capabilities inherent to a visualization tool.