Trace one firm's year back to its company record

Try this

Select one firm before reading the annual line, then trace a row into its company summary lookup.
Brush negative investment changes and inspect the intersection with the selected firm.
Clear the firm selector and confirm that base firm-year count is preserved, not multiplied by the lookup.

Limits

These selected historical firms are not a random sample of all businesses. First differences remain observational and can amplify measurement noise. Source monetary units are retained without an unverified multiplier.