Morningstar performs extensive data cleaning and standardization with the goal of maintaining consistency, accuracy, and comparability across investment vehicles, time periods, and data sources.
Examples include:
- Holdings standardization: Securities can be reported under different names, identifiers, or structures across filings and our standardization process is designed to enable consistent portfolio analysis across funds and make it easier to identify which portfolios own a specific security.
- Share-class and structural normalization: Data for funds with multiple share classes, fee schedules, or historical restructurings are reconciled into continuous, point-in-time-accurate records.
- Performance and net asset value reconciliation: Daily returns and NAVs received from fund companies or service providers are validated to identify and correct discrepancies.
- Historical continuity and survivorship controls: Morningstar maintains records for terminated, merged, or renamed funds to prevent survivorship bias and preserve long-term performance and flow histories.
- Portfolio and classification consistency: Portfolio holdings and asset allocations are mapped to sector, asset-class, and style frameworks, even as reporting conventions and fund mandates evolve.
We seek to apply these processes consistently across SEC-registered funds and privately sourced vehicles, with a focus on enabling reliable longitudinal analysis that cannot be achieved through raw source data alone.