What it means
The naming convention comes from the share classes themselves. Series A preferred stock is created for the first institutional round, Series B preferred for the next, and so on, with each class carrying its own price, rights and protections written into the company's constitution.
Each letter tends to correspond to a stage of proof. Series A funds finding a repeatable sales motion, Series B funds scaling what works, Series C and beyond fund expansion into new markets, acquisitions or the run-up to a public listing or sale.
The rounds stack in a specific way that founders often underestimate. Later investors typically sit ahead of earlier ones in a liquidation, so a Series C holder may be repaid before Series B and Series A in a sale, which changes who actually receives what when the exit price is modest.
Dilution accumulates across the alphabet. Giving away 20% in each of three rounds does not leave founders with 40%, because each round dilutes what remains, and an employee option pool expanded at every stage takes a further slice.
Letters beyond D or E are worth reading carefully. A long alphabet can mean a genuinely capital-hungry business such as hardware or biotech, or it can mean a company that keeps needing money without reaching the milestones that would let it stop raising.
In practice
Real-world examples.
Example
A logistics software company closes a $6,000,000 Series A on the strength of $1,800,000 of recurring revenue, then a $22,000,000 Series B eighteen months later once revenue passes $7,000,000. The B investors take two board seats and insist on a formal budgeting process the founders had previously run informally.
Example
A battery materials startup reaches Series E because building pilot plants consumes capital long before any commercial sales. Each round is justified by an engineering milestone rather than revenue, and the investor base shifts from venture funds towards infrastructure and strategic corporate money.
Example
A consumer app raises a Series C at a valuation it cannot grow into, then eighteen months later takes a Series D at a lower price. The down round triggers anti-dilution protection for the Series C holders, and the founding team's combined stake falls from 34% to 19%.
Formula
Calculation
Price per share = pre-money valuation / shares outstanding before the round
New shares issued = amount raised / price per share
Investor stake = amount raised / post-money valuation
Founders start with 8,000,000 shares. In the Series A the company raises $4,000,000 at a $16,000,000 pre-money valuation, so the price is $16,000,000 / 8,000,000 = $2.00 and the round creates $4,000,000 / $2.00 = 2,000,000 shares. Total shares become 10,000,000, the post-money valuation is $20,000,000, and the Series A investor holds 2,000,000 / 10,000,000 = 20%.
The Series B raises $13,500,000 at a $45,000,000 pre-money valuation. The price is $45,000,000 / 10,000,000 = $4.50, creating $13,500,000 / $4.50 = 3,000,000 shares for a total of 13,000,000, and a post-money valuation of $58,500,000. The Series B investor holds 3,000,000 / 13,000,000 = 23.08%.
The Series C raises $21,000,000 at a $91,000,000 pre-money valuation, so the price is $91,000,000 / 13,000,000 = $7.00 and the round creates 3,000,000 shares, taking the total to 16,000,000 against a post-money valuation of $112,000,000. The Series C investor holds 3,000,000 / 16,000,000 = 18.75%, and the founders' unchanged 8,000,000 shares now represent 8,000,000 / 16,000,000 = 50% of a far larger company.Case study
Seen in the real world.
This is an illustrative and fictional scenario. Windermere Payroll, an invented workforce software company, raised a $5,000,000 Series A, an $18,000,000 Series B and a $40,000,000 Series C over five years, and the founders tracked only one number through the whole process: the headline valuation, which had climbed from $25,000,000 to $210,000,000.
What they had not modelled was the stack of liquidation preferences. Each round carried a 1x preference, so the three investor groups together were entitled to $5,000,000 + $18,000,000 + $40,000,000 = $63,000,000 off the top of any sale before ordinary shareholders received anything, and the Series C money ranked first.
When a strategic buyer offered $95,000,000, the preferences absorbed $63,000,000 and the remaining $32,000,000 was shared among all holders. The illustrative founders, holding 31% of the ordinary shares, received roughly $9,900,000 between them, considerably less than the headline price had led them to assume. The lesson the fictional team shared afterwards was that in alphabet rounds the terms compound just as surely as the dilution does.
Watch out
Common mistakes.
- Assuming a later letter automatically means a better company, when it can equally mean a business that has needed repeated rescues.
- Adding dilution percentages together across rounds, when each round dilutes the remaining stake rather than the original one.
- Ignoring how the liquidation preferences from every round stack up, which decides who gets paid first in anything other than a very large exit.
Questions
People also ask.
Do the letters have to run in order?
In practice yes, though companies sometimes insert an A-1, B-1 or extension round when they raise more on similar terms without repricing the whole company.
What is a bridge round?
A short-term financing, often a convertible note, that carries a company between lettered rounds when it needs time to hit the milestones the next round requires.
When do the letters stop?
Usually at an exit, whether a sale or a public listing, though some private companies keep raising into F, G and beyond while staying private.
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