When an accredited investor buys a membership interest in a special purpose vehicle (SPV), they are not buying shares directly. They are buying an economic interest in a legal entity that holds shares — or contractual rights to shares — in a private company. That distinction creates a dilution problem most buyers only discover after a new primary round closes.
How dilution works at the company level
Every time a private company issues new equity — in a primary fundraising round, through employee stock option grants, via a convertible note or SAFE conversion, or through a warrant exercise — the total share count grows. Existing shareholders own a smaller percentage of the company. This is standard dilution and every equity investor, direct or indirect, faces it.
What matters for secondary buyers is how much that dilution has already happened and how much more is likely before exit. A company that raised a Series A at a $500 million valuation, a Series B at $2 billion, and is now rumored to be raising a Series C has issued meaningful new equity at each stage. The secondary price you pay today should reflect the current capitalization, not the cap table as it existed two years ago.
Reading the most recent 409A valuation — an independent appraisal of fair market value required by the IRS for option grants — gives you a proxy for current common stock value. But 409A valuations lag the market, sometimes by six months or more, and they typically reflect a discount to preferred share value. They do not tell you how many additional shares are authorized and unissued, or how large the option pool is.
Why SPV buyers face an additional layer
Direct shareholders — employees and early investors who hold shares on the company's cap table — receive anti-dilution protection in some circumstances. Broad-based weighted-average anti-dilution provisions, for example, adjust the conversion ratio of preferred shares downward if the company raises a new round at a lower price (a "down round"). If you hold preferred shares directly, that provision can partially protect you.
SPV investors typically do not hold preferred shares. Most secondary SPVs hold common shares or economic rights that track common shares. Common stock carries no anti-dilution protection. A down round or a new preferred issuance simply dilutes common holders without any compensating adjustment. You feel the full impact.
There is a second layer specific to the SPV structure itself. The SPV's operating agreement sets a fixed number of membership units. The GP cannot issue more units without amending the agreement. So within the SPV, your percentage interest is fixed. But the shares that SPV holds can still be diluted at the company level. Your fixed slice of the SPV is worth a smaller slice of the company every time new equity is issued downstream.
The option pool: the dilution source buyers most often miss
Private companies maintain an equity incentive pool — typically 10–20% of fully diluted shares — to grant options to employees and advisors. Options that are authorized but ungranted still appear in the fully diluted share count used in most valuation calculations. When those options vest and are exercised, new shares are issued and existing shareholders are diluted.
For fast-growing companies, the board may approve option pool increases between funding rounds to continue recruiting. These increases are approved by existing shareholders in board votes, which common holders and SPV investors rarely have the standing to influence. The expansion simply happens, and your effective ownership percentage decreases.
Before buying, ask the seller or the marketplace for the most recent fully diluted cap table summary. The relevant number is not the basic share count. It is the total assuming full conversion of all preferred shares, full exercise of all outstanding options and warrants, and conversion of any outstanding convertible instruments (SAFEs, notes). That total denominator tells you what your ownership fraction actually looks like today.
Modeling dilution into your entry price
The practical method is to build a simple ownership waterfall before you finalize an indication. Start with the number of shares the SPV holds (ask the marketplace or review the SPV operating agreement). Divide by the current fully diluted share count to get your implied ownership percentage of the company. Then stress-test that percentage against two or three scenarios: a flat round at the current valuation, a 20% up-round, and a 20% down-round.
For each scenario, estimate the new fully diluted share count after the hypothetical round closes (including any new option pool expansion the board might authorize simultaneously). Recalculate your ownership percentage. Then apply your target exit multiple to the post-round company valuation and trace the distribution through the liquidation waterfall — preferred shareholders get paid out first at their liquidation preference before any proceeds flow to common. What you are left with is a range of common-share exit values that reflects realistic dilution rather than today's snapshot.
This exercise will not give you a precise answer. Private company data is incomplete by nature. But it forces you to separate the question "Is the company doing well?" from the question "Will common shareholders benefit proportionally?" Those two questions can have very different answers, and the gap between them is where SPV buyers most often get surprised.
What to look for in the SPV documents
When you receive the SPV operating agreement before signing, look for three specific provisions related to dilution protection.
- Follow-on rights: Does the SPV have any contractual ability to participate in future rounds to maintain its ownership percentage? Most secondary SPVs do not. If the SPV cannot buy into subsequent rounds, your ownership percentage will decline with every new issuance.
- Pro-rata rights pass-through: If the seller originally held pro-rata rights (the right to invest in future rounds at their current ownership proportion), did those rights transfer to the SPV? Rights attached to specific share classes or individual holder agreements usually do not survive a secondary transfer.
- Drag-along and conversion mechanics: Understand how the SPV's common shares behave at exit relative to the preferred shareholders above them in the waterfall. The operating agreement should specify whether distributions are made pro-rata to SPV members after the GP deducts its carry.
At Limen Markets, our templated SPV documents make the economic terms legible before you commit. The carry rate, management fee (if any), and distribution waterfall are disclosed in the term sheet, not buried in a 60-page partnership agreement you receive after your funds are wired.
The bottom line
Dilution is not a reason to avoid SPV investments in private companies. It is a factor to price correctly. Buyers who ignore it tend to overpay relative to their actual economic exposure. Buyers who model it honestly — even roughly — develop a more defensible view of entry price and can negotiate accordingly.
If you are evaluating a current listing and want to work through the cap table math, review the available materials on our marketplace and reach out to our transaction team before submitting an indication. Understanding what you own before you own it is the work that compounds over time.