409A Valuation After a Series B or C Round: What Changes

Yes, You Need a New 409A After Series B or C

The first question many founders and CFOs ask after a Series B or C close is whether the prior 409A still works for grants made in the next several months. The answer is no. A priced equity round is a material event under Treasury Regulations Section 1.409A-1(b)(5)(iv)(B), and the independent appraisal safe harbor that protected option grants under the prior valuation does not extend to grants made after the new round closes.

This is true regardless of whether the round was a strict up-round, a flat round, or a down round. The fact pattern that triggers the refresh requirement is not the direction of the price change but the existence of a new arm's-length transaction that establishes a new enterprise value. Even a small Series B at terms close to the Series A still constitutes a material event for 409A purposes.

For a deeper discussion of the timing question and how fast you need to refresh after closing, see our companion article on how fast to refresh your 409A after a funding round. The short version: most companies aim to have the refreshed signed report in hand within 30-60 days of close, and pause new option grants in the interim.

Why the Refresh Is Mandatory: The Material Event Rule

The independent appraisal safe harbor under Treasury Regulations Section 1.409A-1(b)(5)(iv)(B) protects option grants from the IRC Section 409A deferred compensation regime when the strike price is set based on a qualifying appraisal. The safe harbor requires that the appraisal not fail to reflect information available after the date of calculation that may materially affect the value of the corporation.

A Series B or Series C closing is precisely the kind of post-calculation information the regulation targets. The new round establishes:

• A new arm's-length price for the company's preferred stock
• An updated capitalization table reflecting the newly issued preferred shares
• A new preferred class with its own liquidation preference, participation terms, and conversion mechanics
• Investor signaling about the company's prospects and timing toward exit

Once any of these material facts changes, the prior 409A no longer reflects current reality. The legal protection of the independent appraisal safe harbor evaporates with respect to grants made after the closing. For the full safe harbor framework, see our 409A safe harbor guide.

What Methodology Changes at Series B vs. Series C

The 409A methodology at Series B and Series C differs meaningfully from Series A. The key shifts:

Multi-class preferred waterfall. At Series A, the OPM backsolve operates against a relatively simple capital structure: founders' common, employee options, and one preferred class. At Series B, you now have Series A and Series B preferred, each with potentially different liquidation preferences (1x non-participating vs. 1x participating capped vs. uncapped), participation rights, and anti-dilution provisions. At Series C, three or more preferred classes are stacked on the waterfall. The OPM must allocate value across each class correctly under each scenario in the waterfall, which is mathematically more demanding than the single-class case.

Anchor price selection. At Series A, the OPM backsolve typically anchors to the Series A round price. At Series B, the appraiser must decide whether to anchor to the Series B price alone, the Series B and Series A together, or some weighted blend. The choice affects the implied total equity value and therefore the common stock value. The general rule is that the most recent round price typically dominates, but the appraiser's judgment matters.

PWERM consideration. At Series C, the probability-weighted expected return method (PWERM) often becomes appropriate alongside or instead of a pure OPM backsolve. PWERM models distinct exit scenarios (IPO, acquisition, continued private operation) with explicit probability weights. The AICPA Practice Aid for equity security valuations describes PWERM as a standard approach for companies with multiple plausible near-term exit scenarios.

DLOM narrowing. The discount for lack of marketability (DLOM) generally decreases as the company moves through funding stages and gets closer to a potential exit. Typical DLOM ranges: Series A (20-30%), Series B (15-25%), Series C (10-20%), late stage with IPO approaching (5-15%). The narrowing reflects the shorter expected time to liquidity and reduced uncertainty about exit timing.

For a deeper methodology discussion of the differences between these stages, see our article on 409A valuation at Series B and Series C: what changes. For the underlying mechanics of the OPM that drives early-stage backsolves, see our option pricing model guide.

Why the Common-to-Preferred Discount Narrows

One question that comes up consistently after a Series B or C close is why the common stock fair market value increases proportionally less than the preferred price did. A founder who saw their Series A preferred price at $2.00 and their Series B at $5.00 might expect the common stock value to rise by a similar 2.5x multiple. In practice, the common stock value generally rises by a smaller factor.

The reasons:

Liquidation preferences absorb the new dollars. The Series B preferred has a liquidation preference (typically 1x of the round amount) that sits on top of the prior preferred preferences. Common stock is the residual claim after all preferred liquidation preferences are satisfied. As more dollars sit ahead of the common in the waterfall, more value is required at exit before common stockholders see any payout.

OPM backsolve mechanics. The OPM allocates value to each class as a series of call options. Each preferred class is essentially a long call on the equity value above the strike point where the prior preferred class's liquidation preference is satisfied. The common stock is also a call option, with a strike at the point where all preferred liquidation preferences and participation caps are satisfied. The mathematical effect is that as the preferred price rises, the implied common value rises but at a flatter slope.

Offset by DLOM narrowing. The narrowing DLOM partially offsets the OPM compression effect. As the expected time to liquidity decreases, the marketability discount applied to the common stock value decreases. The net effect on the common stock fair market value is the product of these two opposing forces.

In practical terms, the common-to-preferred ratio at Series A might be around 25-35% of preferred price. After a Series B, it commonly rises to 30-45%. After a Series C, it may reach 40-55% of the most recent preferred price, depending on the cap table and proximity to exit. The exact figures depend on the specific terms of each preferred class.

Cost Benchmarks for Post-B and Post-C Refreshes

Cost ranges by provider type for post-Series B and post-Series C 409A refreshes:

The cost increase from Series A to Series B largely reflects the additional waterfall complexity. The further increase from Series B to Series C primarily reflects PWERM modeling work and the more rigorous documentation expected at later stages. For a full view of cost benchmarks across stages, see our guide to 409A valuation cost in 2026.

PWERM Considerations: When to Layer In Exit Scenarios

At Series A, the time to exit is generally too distant and uncertain for explicit PWERM scenario weighting to add meaningful precision. The OPM backsolve is the standard methodology and produces a defensible common stock value.

At Series B, PWERM may or may not add value. If the company has a clear path to potential exit within 24-36 months — for example, strong unit economics, a defined product-market fit, and clear comparable acquisition activity in the sector — an appraiser may apply a hybrid OPM/PWERM approach where the OPM produces the baseline allocation and PWERM scenarios are layered in to capture the IPO and acquisition cases.

At Series C, PWERM is increasingly appropriate. Companies at this stage are generally 18-36 months from a potential liquidity event, and the probability and timing of exit scenarios are observable enough to make scenario weighting tractable. The AICPA Practice Aid explicitly discusses PWERM as a standard approach at this stage.

A typical Series C PWERM models three scenarios:

• IPO scenario: The company files an S-1 within a defined timeframe, prices at a range informed by comparable public company multiples, and common stockholders receive value based on the IPO price less underwriting discount and lockup-period DLOM.
• Acquisition scenario: The company is acquired at a strategic premium within a defined timeframe, with the acquisition price distributed through the preferred waterfall.
• Continued private operation: The company raises another round or remains private for an extended period, with value determined by an OPM anchored to the next expected financing or DCF analysis.

The probability weights are determined by the appraiser based on company-specific factors and sector dynamics. The PWERM result is the probability-weighted average of scenario values. This is more appropriate than a pure OPM backsolve at late stage because there are observable market signals about exit timing that make the scenario weighting meaningful.

Common Mistakes Companies Make on Their First Post-B or Post-C 409A

Continuing with the same provider without checking capabilities. The provider that handled your Series A may not have the multi-class waterfall capabilities or PWERM modeling expected at Series B or C. Confirm that the provider has handled comparable cap tables before assuming continuity is the best choice.

Granting options on the prior 409A after closing. The most common mistake is assuming the prior 409A still works for the next several months. It does not. Pause grants until the new signed report is in hand.

Underdocumenting the multi-class waterfall. A defensible Series B or C report should explicitly describe each preferred class's liquidation preference, participation terms, conversion mechanics, and any anti-dilution provisions. Reports that gloss over these details create audit defensibility issues.

Skipping PWERM at Series C. An appraiser who applies only an OPM backsolve to a Series C company that is 18-24 months from a potential IPO is using a methodology that understates the relevance of the exit scenarios. The IRS and SEC both watch for this when reviewing late-stage option grants.

Ignoring secondary transaction evidence. Series C companies often have employees and early investors who have participated in secondary sales. These observed prices for common or preferred stock are evidence the appraiser must address. A report that omits known secondary transactions is incomplete.

Backdating grants to before the round closing. The temptation to date grants to a period when the prior 409A was valid is real but the consequences are severe. Stock administration audits and pre-IPO due diligence specifically look for grant date manipulation. The remediation cost vastly exceeds the inconvenience of waiting for the new valuation.

How to Pick the Right Provider for Your Post-B or Post-C Refresh

Selection criteria for a Series B or C refresh provider:

Multi-class waterfall capability. Confirm the provider's OPM handles three or more preferred classes simultaneously, with anti-dilution and participation features. Ask to see a sample report from a comparable company.

PWERM capability (especially for Series C). Ask the provider to show you a sample report for a Series C company that includes PWERM analysis. Evaluate whether the PWERM section is substantively documented — specific scenarios with named expected values, explicit probability weights with documented rationale.

Credentialed appraiser sign-off. The independent appraisal safe harbor requires sign-off from a person with the appropriate qualifications. For Series B and C, look for ASA, ABV, or CFA credentials.

Turnaround speed compatible with your grant cadence. Companies that grant frequently need providers that can deliver in days or weeks, not months. For specific stage-by-stage provider recommendations, see our guides to Series B 409A providers and Series C and late-stage 409A providers.

Investor and underwriter compatibility. If you have institutional investors with specific 409A provider expectations, or if you anticipate engaging investment bankers for an IPO process within 24 months, check whether your investors and bankers have views on acceptable providers. The wrong provider name in a pre-IPO due diligence package can create unnecessary friction.