Dilution Math Founders Don’t Understand Until It’s Too Late

Founders universally underestimate what a series of “normal” dilution events compounds to over a full financing arc from seed to exit. The specific arithmetic is not taught anywhere except by getting your equity crushed once. As CEO and Chairman of a public mining company, I signed off on dilution structures that would horrify a first-time founder. Here is what I learned about which dilution actually matters and which is noise. · Juan Vegarra

Every founder has a mental picture of what they will own at exit. The picture is almost always wrong. It is wrong not because the founder is unrealistic about valuation. It is wrong because the arithmetic of compounding dilution is genuinely counterintuitive, and the moments where the compounding accelerates are exactly the moments where the founder is least likely to be paying attention to the math.

The median SaaS founder-CEO at IPO owns roughly 8 to 10 percent of the company, according to Carta data across more than 40,000 startups.^[1] Across 124 recent SaaS IPOs analyzed by Blossom Street Ventures, the median combined founder ownership at IPO was 14 percent, with an average of 19 percent when the top two co-founders are combined.^[2] The extremes are more instructive than the medians. The founder of DocuSign, Thomas Gonser, owned 1.5 percent at IPO. Pandora co-founder Tim Westergren owned 2.39 percent before Pandora went public, after the company had endured over 300 VC rejections during the dotcom bust and eventually secured funding at brutal terms.^[3]

Those numbers are not anomalies. They are what happens when a company takes a long path through capital markets and each round dilutes on top of the prior round. The founder who mentally carries 20 percent from the seed round to the exit is running a model that ignores five to seven rounds of intervening compounding.

What the standard round dilution looks like

Carta’s data on venture rounds shows median seed dilution around 20 percent, median Series A dilution around 17.9 percent as of early 2025, Series B typically 15 percent, and Series C and D in the 10 to 15 percent range.^[4] If you assume a founder starts at 100 percent ownership and takes a seed round at 20 percent dilution, a Series A at 20 percent, a Series B at 15 percent, a Series C at 12 percent, and a Series D at 10 percent, the founder’s post-round ownership after five rounds is not 100 minus 77. It is 100 times 0.80 times 0.80 times 0.85 times 0.88 times 0.90, which equals roughly 43 percent.

That is the raw compounding math. It does not yet include the option pool refreshes that typically get created out of the founder’s ownership pre-round rather than the investor’s post-round. It does not include the secondary sales that founders sometimes take at Series C or D, which are dilutive in effect even though they are not technically new share issuances. And it does not include the pay-to-play or ratchet provisions that trigger when a down round happens.

After those adjustments, the same 100 percent starting point typically ends up in the 10 to 20 percent range at IPO for a founder-CEO who has taken five or six rounds. The founder who was mentally modeling 30 to 40 percent is off by a factor of two to three. And the difference is almost never explained to them by the investors who benefit from the compounding.

The mining version is more brutal

The mining seat teaches this math in a different vocabulary. Junior mining companies in Canada rely heavily on flow-through shares, which are a specific instrument that allows the company to renounce Canadian exploration expenses to individual shareholders in exchange for a tax deduction the shareholder can claim personally. The instrument is powerful because it lets the company raise exploration capital at a premium to the market price, since the tax deduction makes the effective cost to the investor much lower than the nominal share price. It is also brutal because every flow-through issuance is dilutive at the operating company level, and the premium the company captured is offset by the ongoing operational cost of continually issuing new shares.

Add rights offerings, which are the mechanism through which a public mining company gives existing shareholders the right to buy new shares at a discount before opening the round to the market. Rights offerings are non-dilutive to shareholders who participate, and severely dilutive to shareholders who do not. In a distressed capital environment, insiders often cannot afford to participate on the terms offered, and the operating team’s ownership gets crushed while external capital claims the discount.

Then add warrant dilution. Warrants are options attached to mining financings that allow the holder to buy additional shares at a fixed price if the stock recovers. Every mining financing during a downcycle attaches significant warrant coverage as compensation for the risk. When the stock eventually recovers, the warrants get exercised, and the operating team’s ownership gets diluted again at exactly the moment when the recovery should have rewarded them.

At Vena Resources through the 2010 to 2015 mining cycle, I signed off on these structures because they were the only viable financing mechanism at the time. Every dilutive event was defensible individually. The cumulative effect over a full cycle was severe, and the founders and early operating team ended up with a fraction of what they would have owned at a company that had never needed the countercyclical financing. That is not unique to mining. It is what happens whenever a company has to raise capital during a downcycle in any capital-intensive industry.

MedTech has its own version

MedTech founders typically end up owning less at strategic exit than SaaS founders end up owning at IPO, and the reason is structural. MedTech companies raise more rounds because the capital requirements are higher. A pre-commercial MedTech company routinely takes six to eight rounds from seed to Series D before FDA clearance, and often needs another commercial round after clearance to fund launch. Each round compounds against the founder’s ownership.

The typical MedTech founder at strategic exit owns 3 to 8 percent of the company. Compare that to the 8 to 10 percent median SaaS founder-CEO at IPO. The gap does not reflect worse governance or worse founder terms. It reflects the additional two to three rounds MedTech companies typically raise to fund the clinical evidence and regulatory work required before revenue. Every round is normal in isolation. The compounding is where the ownership disappears.

Founders who are told their share of a $300 million MedTech acquisition will be $12 to 24 million are working from realistic math. Founders who mentally modeled $60 million from a 20 percent ownership assumption are working from math that never survived contact with the actual round-by-round compounding.

The moments that compound the fastest

Three specific moments accelerate dilution beyond what the standard math predicts. The founder who understands these moments can occasionally negotiate around them. The founder who does not tends to sign the papers.

The first is the option pool refresh at Series B or Series C. Investors typically require the pool to be created or expanded from the pre-money valuation, which means the founder absorbs the dilution and the incoming investor does not. A 15 percent pool expansion at Series C, absorbed pre-money, is roughly 15 percent additional founder dilution that shows up nowhere in the round’s headline dilution number. Over three refreshes, this compounds into another 10 to 12 percentage points of founder dilution beyond what the round-level math suggests. The mechanism is documented in the term-sheet literature and is standard practice at nearly every priced round.^[6]

The second is the participating preferred at Series B or later. Participating preferred means the investor gets their money back first at exit, and then also participates in the remaining proceeds pro rata with common. In a moderate exit scenario, this can consume 15 to 25 percent of the founder’s effective proceeds without appearing as dilution on the cap table. The dilution is real. It just shows up in the waterfall rather than in the ownership percentage.

The third is the down round. A down round almost always triggers anti-dilution protections that convert investor preferred to common at a lower conversion price, which effectively increases the investor’s share count without adding any capital to the company. The founder’s percentage drops without new money coming in. Anti-dilution provisions vary in aggressiveness, but even weighted-average anti-dilution can produce 3 to 8 percentage points of additional founder dilution in a down round that the founder did not anticipate. The NVCA model documents that dominate private financing describe the mechanics of broad-based weighted average anti-dilution as the industry default, and full-ratchet variants remain in circulation for later-stage financings under stress.^[7]

What the CEO seat teaches you about this

The specific thing the CEO seat teaches you about dilution math, and that founder-CEO seats often obscure, is that you cannot negotiate the round-by-round math after the fact. You can only structure the operating plan to require fewer rounds. Every avoided round is 15 to 20 percentage points of founder ownership preserved. Every additional round is 15 to 20 percentage points given up. There is no intermediate option.

The founder-CEO who cannot install the operational discipline to hit milestones on plan takes an extra round. The founder-CEO who takes an extra round dilutes from 30 percent to 24 percent, from 24 percent to 19 percent, from 19 percent to 15 percent. Each round looks defensible. The cumulative effect is that the founder who could not stay on plan ends up owning half of what the founder who did ends up owning, on the same company at the same exit valuation. That is what CFO discipline and board discipline actually buy you at exit.

None of this is taught in the standard founder education. It is taught by watching your first company go through five rounds and looking at what you own at the end. The founders who have been through this once are the ones who structure differently the second time. The founders who have not been through it yet are the ones running the math that assumes 30 percent at exit while the compounding quietly delivers 12 percent.

What I would tell my earlier self

The dilution math is not the enemy. The enemy is the round you did not need to take. Every dollar of capital raised that could have been avoided by hitting a milestone on plan, or by extending runway through operational discipline rather than a new round, is dollars of eventual founder ownership preserved. The math is unforgiving. It is also predictable. Founders who model it round by round, all the way through to exit scenarios, make different capital decisions than founders who model it round by round through Series B and then hand-wave the rest.

The specific number I would give any first-time founder is this: if you are mentally carrying a founder ownership assumption above 20 percent at exit, and you plan to raise more than three institutional rounds, your assumption is wrong. Run the math with real compounding, real option pool refreshes, and realistic down round scenarios. Whatever you own in that model is closer to what you will actually own than the number you started with. It is worth knowing before you sign the next round rather than after.

Juan Vegarra is the author of An Outsider’s Playbook (2026). He signed the dilution structures at Vena Resources through a full mining commodity cycle. More essays · Free toolkits · Advisory · Write me