Pick the method last. | LHM Valuation Group

The question that gets asked first in growth-company equity work is almost always the wrong one. Whether to use OPM, PWERM, a hybrid, or Monte Carlo is a downstream decision. Upstream are the company’s actual facts: stage, capital structure, rights and preferences, real transaction evidence, the likely path to liquidity, and what the accounting consequences look like if a recent secondary included anything other than fair value. Pick the method first and the model is doing work the facts don’t support.

That framing isn’t new, but it just got reinforced. The AICPA released its updated Valuation of Privately-Held-Company Equity Securities Issued as Compensation working draft on December 18, 2025, with comments due June 1, 2026. PwC expects finalization in late 2026 or early 2027. The draft is nonauthoritative until then, but the Big Four are uniformly telling clients to consider it now and reassess current practice. The draft sharpens what calibration requires, when secondary transactions are admissible, and how to handle the compensatory element under ASC 718. None of that is theoretical anymore, because the market is generating the kinds of transactions the draft addresses.

Methods, in plain English

Figure 1

Four tools for four different problems, not a hierarchy.

Method	Best fit when	Main strength	Main risk if misused
OPM	Future liquidity is hard to forecast; outcomes spread across a wide continuum; cap-table rights matter more than a few specific exits.	Efficient allocation of current equity value across complex preferences and breakpoints.	Smooths a lumpy fact pattern; understates the importance of identifiable near-term paths.
PWERM	Late-stage facts support a small number of explicit IPO, M&A, or downside scenarios that can each be modeled with specificity.	Transparent link between specific outcomes and value; aligns with how market participants actually think.	Looks precise while resting on fragile probability and timing inputs.
Hybrid	Near-term exits are visible, but if they don’t happen, the company stays private along a much wider distribution.	Combines explicit scenarios with within-scenario allocation; captures both views.	Easy to over-engineer; internal inconsistency between OPM and scenario inputs.
Monte Carlo	Path dependence, triggers, convertibles, warrants, earnouts, or within-scenario variability make endpoint methods incomplete.	Captures full distributions and path-sensitive payoffs that simpler models lose.	Becomes a black box if assumptions aren’t observable, explainable, and individually testable.

The draft describes these as different tools, not a complexity ladder. A more elaborate model can look more rigorous and still rest on weaker support.

How the facts actually pick the method

The draft offers a clearer framework for matching the model to the company’s posture. Walking it through with real fact patterns:

Figure 2

The fact pattern leads and the method follows.

OPM Often appropriate

Early-stage company with no clear exit path; many strategic choices remain; outcomes span a wide continuum, or the distribution is bimodal but breakpoints still drive allocation.

PWERM Or hybrid, more often

Late-stage company with one or more plausible IPO and M&A paths that can be modeled with real specificity. Greater visibility into actual exits raises the case for explicit scenarios.

Hybrid Two views, one model

Visibility into a near-term exit, but if that doesn’t happen, broad uncertainty about delayed outcomes. OPM mechanics inside the “remain private” scenario.

Monte Carlo When path matters

Convertibles, warrants, earnouts, ratchets, or path-dependent rights where simpler models would omit economically important features.

Late-stage does not automatically mean PWERM. Greater transparency into actual paths raises the case for explicit scenarios, but if the scenarios still carry significant uncertainty, hybrid mechanics often fit better.

A model with more moving parts looks more rigorous than it usually is.

Why calibration is no longer optional

The biggest practical theme in the draft is not a push toward any one method. It is an instruction to use observable evidence, and to use it with care rather than mechanically. Chapter 8 says calibration is required when an observed transaction is still relevant at the measurement date. Subsequent fair value measurements have to incorporate that calibration, plus any other observable transaction prices the company has. Chapter 6 adds that calibration should be used, where possible, to mitigate the difficulties in scenario work. A defensible valuation explains what the transactions imply and how they change the model, rather than looking away from them.

Principal-market analysis is a central part of that exercise. ASC 820 defines the principal market as the one with the greatest volume and level of activity for the asset. The draft emphasizes that this analysis is required when assessing private-company transaction evidence. A tender, brokered transaction, or insider sale is data whose relevance depends on where the security would actually trade from a market-participant perspective.

The market is forcing the issue

The reason calibration moved from background concept to operating discipline is the volume of observable evidence in the private market. The numbers from 2025:

Figure 3

Private-market liquidity, 2025.

396 +62%

Tender offers conducted on Carta’s platform in 2025, up from 244 in 2024

Carta

~20%

Of those tenders came from Series E or later companies

Carta

$106B

U.S. venture secondary transaction value, 2025

PitchBook

Case study · Stripe employee tender pricing

Feb 2025$91.5B

+74%

Feb 2026$159B

Sources: Carta 2025 in Review & H1 2025 tender-offer analysis; PitchBook 2025 Annual U.S. VC Secondary Market Watch; Stripe newsroom releases (February 2025; February 2026). The Stripe data point is not representative of the broader market, but the speed of repricing is what makes calibration unavoidable.

The volumes alone are too large to wave away as anecdotal. When a company’s own tender, repurchase, or organized secondary sits in the file, the valuation has to confront it: weight it heavily, adjust it materially, or set it aside, with reasoning a reviewer can audit.

Common audit and board questions

Why not just use the last preferred round?

Because Chapter 8 says primary transactions often aren’t themselves transactions in the principal or most advantageous market for the common stock being valued. A preferred financing can be powerful calibration evidence. It is not the same thing as treating common as preferred minus a generic discount.

Why not just use the latest tender price?

Because the draft says secondary transactions sometimes include other elements, including compensation. Chapter 9 specifically asks whether the company benefited from or actively facilitated the transaction. If the price embeds a bonus-like element or strategic consideration, it may be inappropriate to incorporate that price directly into the post-transaction fair value of common.

Why not always use the most sophisticated model?

Because the draft describes trade-offs, not a hierarchy. PWERM can be conceptually attractive but hard to implement; OPM is appropriate in some uncertain settings; hybrid fits when explicit near-term scenarios coexist with broader uncertainty. Complexity isn’t the same thing as defensibility.

How do we explain a gap between a recent common-stock value and an IPO range?

The SEC expects a bridge, not a hand-wave. Recent registrant correspondence walks through OPM, PWERM, hybrid weighting, secondary-transaction influence, DLOM, preferred conversion at IPO, and post-valuation milestones. Cheap-stock comments still focus on differences between common-stock valuations and anticipated IPO pricing, especially when investors recently bought similar securities at much higher levels.

The takeaway

Method selection in 409A and growth-company equity valuation is a judgment call grounded in facts, not a loyalty test for OPM, PWERM, hybrid, or Monte Carlo. The harder calls now are calibration and how to treat secondary evidence. Both have to be confronted directly when the evidence is relevant, which it increasingly is. A commodity 409A report stops being enough when complex preferences, recurring tenders, audit scrutiny, pre-IPO planning, or compensatory secondaries enter the picture. In those settings, the value comes from judgment that can reconcile business value, security terms, observable trades, and reporting standards into a conclusion that holds up. The model itself is the easier part.