How Valuers Calculate 409A FMV (OPM, Backsolve, PWERM Explained Simply)

409A valuations may look complex, but the logic behind the calculation can be understood easily when broken into simple components.

1️⃣ Option Pricing Model (OPM)

Used when your startup is early-stage or has multiple preference rights.
It treats equity like financial options and considers factors like volatility, liquidation preferences, and discounts.

Best for: Pre-Seed, Seed, early Series A companies.

2️⃣ Backsolve Method

Used when you recently raised a round.
The valuer takes your preferred share price from the funding round and “backs into” the common share value based on rights and preferences.

Best for: Startups with a funding round in the last ~6 months.

3️⃣ PWERM (Probability Weighted Expected Return Method)

Used when a company has multiple possible outcomes (acquisition, IPO, down-round).
The valuer estimates outcomes → assigns probabilities → calculates today’s value.

Best for: Growth-stage companies or uncertain exit timelines.

4️⃣ DCF (Discounted Cash Flow)

Used rarely for early-stage startups, because revenue & cash flows are unpredictable.
More common for late-stage companies.

Each method has its place. A good 409A valuation chooses the right model based on stage, cap table, and funding history—ensuring audit-proof FMV.