Illiquid securities are financial instruments that cannot be sold quickly at or near their fair value, either because too few buyers are active in the market or because legal restrictions block a fast resale. A share of a large-cap stock on the NYSE trades in seconds; a stake in a private company or a small municipal bond may take months to unload, and only at a discount. Most of the practical problems investors face sit somewhere between those extremes, and they show up as wider spreads, valuation guesswork, and tax rules that punish delay.
How to Tell a Security Is Illiquid
Low trading volume is the clearest sign. When few shares change hands on a given day, a seller has to wait for a buyer or accept a worse price. That scarcity widens the bid-ask spread, the gap between what buyers are offering and what sellers will take. On a heavily traded stock, the spread might be a penny or two. On a thinly traded security, it can run to dollars, so you lose real money simply entering or exiting.
Shallow market depth adds a second cost: slippage. If you try to sell even a moderate block, there may not be enough resting buy orders at the top price to absorb it. The order fills across progressively lower bids, and the average execution price drops. Investors who have never lived through this tend to underestimate how much it costs to sell something no one is actively trying to buy.
Common Examples of Illiquid Securities
Restricted Securities
Restricted securities are shares acquired outside the public markets, typically through private placements, employee compensation plans, or offshore transactions. They carry a legend on the certificate, or a notation in book-entry form, warning that they cannot be freely resold. Common examples include shares purchased in Regulation D private placements, Rule 506(b) and 506(c) offerings, and stock received under employee benefit plans through Rule 701.1U.S. Securities and Exchange Commission. Private Secondary Markets
Before restricted securities can be sold publicly, the holder usually has to satisfy SEC Rule 144. The minimum holding period is six months if the issuing company files periodic reports with the SEC, or one year if it does not. Company affiliates (officers, directors, and large shareholders) face extra hurdles even after the holding period ends. They can sell only the greater of 1% of the outstanding shares or the average weekly trading volume over the prior four weeks in any three-month period, and sales must be handled as routine brokerage transactions with no solicitation.2U.S. Securities and Exchange Commission. Rule 144: Selling Restricted and Control Securities For OTC stocks, only the 1% measurement applies, which can make it nearly impossible to sell a meaningful position quickly.
Private Equity and Venture Capital Interests
Private equity funds typically operate as limited partnerships with a contractual life of about ten years and offer no redemptions during that period.3Morgan Stanley. An Introduction to Private Equity Basics You commit capital, the fund calls it over several years, and you wait for the manager to sell portfolio companies and distribute proceeds. Holding periods have been stretching. A 2025 analysis found the telecom and media sector averaged 7.27 years, and fund managers acknowledged that once holdings reach seven or eight years, pressure to exit intensifies.4S&P Global Market Intelligence. Private Equity Buyouts Record Longer Holding Periods in 2025
Penny Stocks
Penny stocks, generally securities priced under $5 per share that trade over the counter, frequently suffer from extreme illiquidity. Some go days or weeks without a single recorded trade. The Penny Stock Reform Act of 1990 directed the SEC to adopt disclosure rules (Rules 15g-2 through 15g-6) requiring broker-dealers to warn customers about the risks of these securities before executing a transaction. Limited public information about many of these issuers makes it hard for buyers to assess value, which thins the pool of willing participants further.
Thinly Traded Bonds
Certain municipal and corporate bonds become effectively illiquid after their initial offering. Small issues from local governments or niche corporate issuers often attract institutional buyers who hold to maturity, taking those bonds out of circulation. If you need to sell before maturity, you may find no active secondary market and have to accept a steep discount from a dealer willing to take the position.
Rules That Keep These Securities Illiquid
Accredited Investor Requirements
Many illiquid investments are only available to accredited investors, which limits the pool of people who can legally buy them on the secondary market. An individual qualifies based on wealth, income, or professional credentials. The financial tests require either a net worth above $1 million (excluding the value of your primary residence) or income above $200,000 individually ($300,000 with a spouse or partner) in each of the prior two years with a reasonable expectation of the same going forward. Professional qualifications also count: holders of the Series 7, Series 65, or Series 82 licenses can qualify, as can directors, officers, and general partners of the issuing company, along with knowledgeable employees of a private fund.5U.S. Securities and Exchange Commission. Accredited Investors
IPO Lock-Up Agreements
When a company goes public, insiders such as employees, early investors, and venture capital backers are typically locked out of selling their shares for a set period. These are contractual agreements between the company, its underwriter, and its insiders rather than direct SEC mandates. Most lock-ups last 180 days, though terms vary and some limit the number of shares that can be sold even after the lock-up expires.6U.S. Securities and Exchange Commission. Initial Public Offerings, Lockup Agreements Companies must disclose the lock-up terms in their registration documents and prospectus.
Mutual Fund Illiquid Asset Caps
Regulators also constrain how much illiquidity institutional funds can take on. Under SEC Rule 22e-4, an open-end mutual fund cannot acquire any illiquid investment if doing so would push its illiquid holdings above 15% of net assets.7eCFR. 17 CFR 270.22e-4 Liquidity Risk Management Programs The cap protects shareholders who might need to redeem, but it also means fund managers actively avoid illiquid securities, shrinking the buyer pool further.
Secondary Markets for Private Holdings
A small but growing ecosystem exists for trading private company shares before an IPO or fund liquidation. These private secondary transactions operate under federal exemptions from SEC registration, most commonly the Section 4(a)(1) ordinary trading exemption, the Rule 144 safe harbor, or the Section 4(a)(7) safe harbor for restricted securities. Even when a federal exemption applies, the resale must also satisfy state securities laws unless the issuer is an SEC-reporting company.1U.S. Securities and Exchange Commission. Private Secondary Markets
Platforms like Forge Global and Nasdaq Private Market match buyers and sellers of pre-IPO shares, but they are not free markets in the way a stock exchange is. Transactions often require the issuing company’s consent, buyers generally must be accredited investors, and pricing is opaque because there is no continuous public quote. Sellers routinely accept discounts of 20% or more from the last funding-round valuation just to get liquidity. These platforms help. They do not make private holdings anywhere close to liquid.
How Illiquid Securities Are Valued
When a security does not trade on a public exchange, there is no market price to point to. Holders and their accountants estimate value using models. The most common approach is a discounted cash flow analysis, which projects the asset’s future earnings and discounts them back to a present value using a rate that reflects the risk involved. The inputs are subjective, and small changes in the growth rate or discount rate produce very different valuations.
Under FASB Topic 820, assets are ranked in a three-level fair value hierarchy. Level 1 uses quoted prices in active markets. Level 2 uses observable inputs from comparable assets. Level 3, the lowest priority, relies on unobservable inputs and applies when there is little or no market activity for the asset. Any illiquid security without comparable publicly traded peers ends up here, and the resulting valuations carry the most uncertainty.
When appraising an illiquid holding, valuators apply a Discount for Lack of Marketability (DLOM) to reflect that the asset cannot be quickly converted to cash. The IRS defines DLOM as “an amount or percentage deducted from the value of an ownership interest to reflect the relative absence of marketability.” The size varies. Academic studies compiled by the IRS show average means and medians around 31% to 33%, with individual discounts ranging from about 8% for safer, shorter-duration holdings to over 80% in extreme cases.8Internal Revenue Service. Discount for Lack of Marketability Job Aid for IRS Valuation Professionals The discount is applied only when earlier steps in the valuation produced a marketable value; if the valuation already accounts for illiquidity, layering on a DLOM would double-count the problem.
Tax Consequences
Worthless Securities
If an illiquid security becomes completely worthless, you can claim a capital loss, but the rules are specific. The IRS treats the loss as if you sold the security on the last day of the taxable year it became worthless, not the day it actually lost its value. That timing determines whether the loss is long-term or short-term based on your total holding period. You cannot deduct a loss for a security that has merely dropped in value; it must be wholly worthless, and you must permanently surrender all rights in it.9eCFR. 26 CFR 1.165-5 – Worthless Securities Investors who sit on a failed private company holding for years without formally claiming the loss often miss the deduction entirely.
Qualified Small Business Stock
One tax advantage available to holders of certain illiquid securities is the Section 1202 exclusion for Qualified Small Business Stock. For stock acquired after July 4, 2025, a tiered exclusion applies based on how long you hold: 50% of the gain is excluded after three years, 75% after four years, and 100% after five years. Stock acquired between September 2010 and that date still qualifies for the full 100% exclusion after five years. The per-issuer gain cap is $15 million, or $5 million for married individuals filing separately, with inflation adjustments beginning for tax years after 2026.10Office of the Law Revision Counsel. 26 U.S. Code 1202 – Partial Exclusion for Gain From Certain Small Business Stock The stock must be in a domestic C corporation with gross assets not exceeding $50 million at the time of issuance, and you must have acquired it directly from the company rather than on a secondary market.
Estate Valuation
Illiquid securities create problems in estate planning because the IRS requires a fair market value for every asset in the gross estate, even those with no public trading history. For stock in closely held or inactive corporations, the executor must provide balance sheets and five years of earnings and dividend history to support the valuation. Interests in partnerships, LLCs, and unincorporated businesses follow similar requirements and must also account for goodwill.11Internal Revenue Service. Instructions for Form 706 (Rev. September 2025) Overvaluing the asset means overpaying estate taxes; undervaluing it invites penalties.
Borrowing Against Illiquid Positions
Illiquid securities are difficult to use as collateral. For an OTC stock to be eligible for margin borrowing, it must meet a long list of requirements under Federal Reserve Regulation T: at least four market makers submitting bona fide quotes, a minimum average bid price of $5, at least 400,000 shares in public float, a minimum of 1,200 shareholders, and the issuer must have been in existence for at least three years, among other conditions.12eCFR. 12 CFR 220.11 – Requirements for the List of Marginable OTC Stocks Most illiquid OTC securities fail several of these tests, so brokers will not lend against them. Even if a security technically qualifies, brokers have discretion to impose higher margin requirements or refuse the position outright. The practical result is that illiquid holdings tie up capital without providing any borrowing power in return.