Equity Dilution

Definition

Equity dilution is the reduction in existing shareholders' ownership percentage that occurs when a company issues new shares — typically during a funding round, option pool creation, or conversion of SAFEs and convertible notes. Modeling dilution through a pro-forma cap table is essential for making informed decisions about how much to raise, at what valuation, and with what option pool size. [src1]

Key Properties

• Dilution formula: New investor ownership = Investment / Post-money valuation
• Median dilution per round: Seed ~19%, Series A ~20-25%, Series B ~15-20%
• Option pool impact: 10-20% of fully diluted shares, created pre-money
• Pre-money vs post-money: Same dollar amount yields very different ownership at each
• Cumulative effect: Founders commonly retain 20-30% after 3 rounds

Constraints

• All convertible securities must be included for accurate modeling [src1]
• Option pool creation pre-money increases dilution for founders, not investors [src2]
• Anti-dilution provisions cause additional dilution in down rounds [src5]
• Pre-money vs post-money confusion is the most common error [src2]
• Companies with clean cap tables raise follow-on funding 67% faster [src4]

Framework Selection Decision Tree

START — Founder needs to understand equity ownership
├── What's the specific question?
│   ├── "How much will I be diluted?" → Dilution Modeling ← YOU ARE HERE
│   ├── "What instrument should I use?" → SAFE vs Convertible Note
│   ├── "How do I set up co-founder splits?" → Founder Vesting
│   └── "How do I manage my cap table?" → Cap Table Management
├── What stage?
│   ├── Pre-seed → Simple: Investment / Post-money = investor %
│   ├── Seed with SAFEs → Include all SAFE conversion in cap table
│   ├── Series A → Model option pool shuffle (pre-money creation)
│   └── Series B+ → Full waterfall with liquidation preferences
└── Is this a down round?
    ├── YES → Model anti-dilution provisions
    └── NO → Standard dilution calculation

Application Checklist

Step 1: Build the current cap table

• Inputs needed: All shares, convertible securities, option grants
• Output: Fully diluted cap table with ownership percentages
• Constraint: Include every instrument — missing any changes all percentages [src1]

Step 2: Define proposed round terms

• Inputs needed: Amount raised, pre-money valuation, new option pool size
• Output: Term sheet parameters for modeling
• Constraint: Clarify pre-money vs post-money explicitly [src2]

Step 3: Model SAFE/note conversion

• Inputs needed: Each SAFE/note principal, cap, discount, interest accrued
• Output: Conversion share counts per instrument
• Constraint: Each converts at better of cap or discount [src5]

Step 4: Calculate option pool shuffle

• Inputs needed: Target pool size (%), current unallocated options
• Output: New shares added, impact on founder ownership
• Constraint: Pre-money pool is the single largest hidden dilution source [src2]

Step 5: Generate pro-forma cap table

• Inputs needed: Outputs from steps 1-4
• Output: Post-round ownership table
• Constraint: Validate percentages sum to 100%; run sensitivity at +/- 20% valuation [src1]

Anti-Patterns

Wrong: Assuming stated valuation determines ownership

A founder hears "$20M valuation" and assumes 80% ownership after a $4M raise. With a 15% pre-money option pool, actual dilution is significantly higher. [src2]

Correct: Model full cap table including option pool

Calculate ownership from the fully diluted share count including option pool, SAFE conversions, and new investment. [src1]

Wrong: Ignoring convertible securities until conversion

Founders surprised at Series A when all SAFEs convert and dilution is 10-15% higher than expected. [src5]

Correct: Track all convertible securities from day one

Every SAFE, note, and warrant should appear on the cap table when signed. Model conversion quarterly. [src4]

Wrong: Raising maximum capital at highest valuation

$10M at $100M sounds great but if the company cannot grow into that valuation, the next round becomes a down round with anti-dilution crushing common shareholders. [src3]

Correct: Raise what you need with 18-24 month runway

Accept a reasonable valuation you can grow into, avoiding the down-round trap. [src3]

Common Misconceptions

Misconception: Dilution is always bad and should be minimized at all costs.
Reality: A smaller slice of a much larger pie is worth more. The goal is optimizing the trade-off between dilution and growth capital. [src3]

Misconception: The option pool comes from the investor's allocation.
Reality: Created pre-money by convention, the pool comes from existing shareholders' ownership. [src2]

Misconception: A higher valuation always means less dilution.
Reality: Higher valuations create expectations; if not met, anti-dilution provisions in down rounds can cause more dilution than a lower initial valuation. [src5]

Comparison with Similar Concepts

When This Matters

Fetch this when a founder asks about dilution impact, pro-forma cap tables, option pool shuffles, pre-money vs post-money differences, or modeling ownership across multiple rounds.