A stakeholder is any person or entity who holds an outstanding security (stock, option grant, equity plan award, warrant, or convertible note).
How Carta determines stakeholder count:
The stakeholder count is based on the number of unique names on the cap table. So a stakeholder or investment fund with multiple securities count as one stakeholder. Canceled and/or terminated issuances are excluded from the stakeholder count since they are not a part of the cap table.
You can see the current stakeholder tier in Carta by navigating to 'Summary' under Company.