Not investment advice. Educational reading. See Disclaimer.
L.12 · ADVANCED · 4 MIN
Private-Company Illiquidity Discount Mechanics
Private-company valuations need a discount that public-company valuations do not: the cost of NOT being able to sell the shares freely. This is the Discount for Lack of Marketability (DLOM), and unlike the cost of equity (where the academic literature provides reasonably tight ranges), DLOM has a wide 20-40% empirical band that depends heavily on the specific marketability constraints of the equity being valued. The advanced practitioner needs to know where the empirical evidence comes from, what moves the discount within the 20-40% range, and how to defend a specific number against an opposing party (buyer vs seller, IRS vs estate, audit vs SOC review).
Discount on Rule 144 restricted public stock vs. unrestricted; SEC 2-year holding period
Restricted-stock studies (post-1997, post-2008)
~20-25%
Same as above; holding period reduced to 1-year then 6-months — discount narrowed mechanically
Pre-IPO studies
~30-40%
Discount on last-private-round shares vs. IPO price (Emory, Willamette samples)
Mandelbaum factors (US Tax Court)
Case-by-case 10-50%
Eight enumerated factors from the 1995 Mandelbaum decision; the legal-defensibility framework
QMDM (Mercer Capital, 1997+)
Computed range, typically 20-35%
Treats DLOM as cost-of-equity uplift over the holding period; most rigorous but most assumption-sensitive
§ 02
The single most important insight in DLOM analysis is that the empirical evidence is wide AND directionally consistent — the 20-40% band is real, and the load-bearing analytical work is choosing a number WITHIN the band that reflects the firm's specific marketability profile, not arguing about which study window produces the right average. A defender who says '30% is the right DLOM here because expected holding period is 5-7 years, distributions are moderate, and there are no put rights' is operating at the right level; a defender who says 'the average across all studies is 28% so the right DLOM is 28%' is conceding the analytical work to whoever has done it more carefully on the other side.
§ 03
QMDM Approx: DLOM = 1 - (1 + r_marketable) ^ H / (1 + r_marketable + DLOM_uplift) ^ H
§ 04
Open the QMDM widget above. Set marketable COE = 11%, uplift = 4%, and walk holding period from 2 years to 10 years. Note how the DLOM moves from roughly 7% (2-year hold, near-IPO firm) to 22% (5-year hold, typical mid-cycle private) to 33% (10-year hold, no exit path). The exercise demonstrates that the 20-40% empirical range is not a single number — it is the range that QMDM produces across realistic holding-period inputs for a defensible illiquidity uplift, which is exactly why advanced practitioners use QMDM to defend a SPECIFIC number rather than citing a population average.
§ 05
An estate-tax valuation of a 15% non-controlling stake in a $200M (marketable equity value) family-owned construction company is being reviewed by the IRS. The 15% stake has no put rights, no tag-along rights, an expected family-internal-exit horizon of 8-10 years, and no recent distribution history (the family typically reinvests). The taxpayer's appraiser claims a 25% DLOM ($7.5M off the $30M pro-rata value). The IRS's expert proposes a 40% DLOM ($12M off). What is the most defensible analytical posture, and which Mandelbaum factors most support a higher DLOM?
§ 06
The historical narrowing of the restricted-stock-study discount — from approximately 35% pre-1990 to approximately 20-25% post-1997 (Rule 144 1-year holding period) to even narrower in some post-2008 samples (6-month Rule 144 holding period) — is the cleanest natural experiment in the DLOM literature. It tells the practitioner that holding period IS the load-bearing driver of marketability discount, not a confounding variable. A firm with a known 12-month exit window deserves a markedly smaller DLOM (10-15%) than a firm with a 5-year expected hold (25-30%) than a firm with no defined exit path (30-40%). This is why the QMDM framework's explicit treatment of holding period as the primary input is the methodologically most defensible approach: it operationalizes the natural experiment that the restricted-stock studies generated by accident.
§ 07
A founder is selling a 5% stake in their private SaaS company at a $400M post-money valuation to a new strategic investor. The investor demands a 35% DLOM. The founder counters that the stake comes with a put right exercisable at fair value after 3 years AND a tag-along right on any subsequent founder sale. What is the disciplined DLOM in light of the liquidity rights?
Five questions · AI feedback
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Sit with the ideas.
You are valuing a private specialty-chemicals company with $80M of EBITDA, an enterprise value of $560M (7x EBITDA on a guideline-public-company basis), and net debt of $120M. The pre-DLOM equity value is $440M. The buyer is considering a 20% minority investment for $88M. A DCF-and-comps cross-check says the marketable-equivalent equity value is sound, but the seller and buyer disagree on the marketability discount. The seller proposes a 20% DLOM ($70.4M off the marketable value); the buyer proposes a 38% DLOM ($167.2M off). What is the most disciplined defense of a midpoint DLOM in the 28-32% range, and what are the three load-bearing inputs that move the discount within the 20-40% band?
