Final answer:
Financial Information Systems (Financial IS) provide financial data crucial for financial managers to make informed decisions and conduct financial analysis within an organization.
Step-by-step explanation:
The financial information that would be most useful to financial managers in an organization is provided by a Financial Information System (Financial IS). This system is specifically designed to manage the organization's financial data, including assets, liabilities, revenue, expenditures, and various financial statements, which are critical for decision-making and financial analysis. Financial IS interfaces with other systems, such as Accounting Information Systems, but its primary purpose is to support financial planning and control functions.