Fully Diluted Shares
Definition
The total number of shares that would be outstanding if every convertible instrument (options, warrants, SAFEs, convertible notes) were converted into shares. This is the denominator you should use when calculating your ownership percentage. Fully diluted share count is always higher than current outstanding shares.
Real-World Example
A company has 8M shares outstanding, plus 2M shares in the option pool (1.5M granted, 0.5M unallocated), plus SAFEs that will convert to 1M shares. Fully diluted: 11M shares. If you have 11,000 shares, your ownership is 0.1% (11,000/11,000,000), not 0.14% (11,000/8,000,000).
Common Mistake
Calculating ownership using only currently outstanding shares. Many offer letters show "X shares out of Y outstanding" but Y may not include unallocated option pool shares, outstanding SAFEs/notes, or unvested grants. Always ask for the fully diluted share count.
Why It Matters
Fully diluted shares give you the most realistic picture of your ownership. Using the wrong denominator can make your equity look 30-50% more valuable than it really is.
Related Terms
Want to learn one equity concept per week?
Read the Newsletter