Series A, B and C Funding Explained
Turn this article into takeaways for your work.
Each assistant summarizes the article only for you and suggests best practices for your work.
Series A, B and C are the lettered rounds of venture financing in which a startup sells preferred stock at a negotiated price per share. The letters are a naming convention for the order of the rounds: A is the first priced round after seed money, B follows it, C follows that, and the alphabet keeps going for as long as the company keeps raising. Cooley GO, a law firm's startup resource, puts it this way: "The stages of series financing typically include Series Seed, Series A, Series B, Series C and so on."
The letter says little about company size on its own. It tells you the sequence. What a round is for, how big it is and who writes the check depend on the company, the market and the year. This article describes the typical pattern in US practice, and rules in other countries can differ.
Where the Letters Come From
Each round creates a new series of preferred stock. Investors in the first priced round buy Series A Preferred, investors in the next buy Series B Preferred, and so on. Each series is its own class with its own price per share and its own rights, which is why the rounds carry letters instead of just dates.
Cooley GO explains that preferred stock "typically carries a liquidation preference, which allows it to get paid ahead of common stock (but after debt)," and that holders "often have the ability to elect one or more members of a company's Board of Directors, and to veto certain significant corporate actions." That is why a Series A is a bigger governance event than a SAFE or note. The investors don't just buy shares. They get a seat at the table and protections that stay with the company through every later round. See liquidation preference for how the payout order works.
Before the first letter, many companies raise a seed round, often on a convertible note or a SAFE. Those instruments convert into the Series A shares when the first priced round closes.
Series A: Scaling Up What Already Works
Series A is usually the first institutional venture round. Cooley GO says the money is used for "scaling up" as opposed to "starting up", and that Series A investors are "usually venture capital funds."
What it typically funds:
- Hiring the first real sales, marketing and engineering teams beyond the founders
- Turning an early product and a handful of customers into a repeatable way to acquire customers
- Extending runway long enough to reach the next set of milestones
What investors look for: evidence of product-market fit, early revenue or usage that is growing, a team that can execute, and a market large enough to justify a venture-sized outcome. The exact bar moves with the market, and there is no universal revenue threshold.
Who leads: a venture capital fund, which negotiates the term sheet and sets the price. The lead investor usually takes a board seat. Other funds follow on the lead's terms. Cooley GO notes that Series A investors often end up with about 20 to 40 percent of the company after the financing. Existing seed investors may also use pro-rata rights to buy part of the round.
Series B: Building the Machine
By Series B, the question changes from "does this work?" to "how fast and how efficiently can it scale?" The company is usually past early validation and is spending to grow.
What it typically funds: expanding sales and marketing capacity, entering new markets or customer segments, building out the product and deepening the management team (finance, people, operations).
What investors look for: growth that is repeatable rather than founder-driven, healthy unit economics, a clear view of how burn rate turns into revenue, and a plan that justifies the larger valuation they are being asked to pay.
Who leads: often a larger venture fund, sometimes joined by growth-stage investors, and existing Series A investors commonly participate.
Series C and Beyond: Growth Rounds
Series C and later rounds are usually raised by companies with a proven business model. The money often goes toward expansion into new geographies, acquisitions, new product lines, or preparing for a later exit. The typical lead is a growth equity fund, a late-stage venture firm or a corporate venture capital arm, and some rounds draw in crossover investors that also buy public stock.
Rounds labeled D, E and beyond exist, and nothing in the system stops at C. Companies reach them when they keep raising private capital instead of going public or being acquired. The usual endpoints are an initial public offering or a sale of the company. For how these stages compare with company maturity, see early-stage vs growth-stage and stages of a startup.
Series A vs B vs C at a Glance
The table below describes common patterns, not rules. There are no fixed round sizes or valuations for any letter, and published medians change every quarter and are heavily skewed by a few very large deals.
| Series A | Series B | Series C and later | |
|---|---|---|---|
| Core question | Can this scale? | Can it scale efficiently? | Can it dominate or exit? |
| Typical use of funds | First real go-to-market and team build | Expansion, new markets, management depth | New regions, acquisitions, pre-IPO growth |
| Typical lead | Venture fund | Larger venture or growth fund | Growth equity, late-stage or crossover investors |
| Evidence investors weigh | Product-market fit, early growth | Repeatable growth, unit economics | Scale, profitability path, market position |
| Risk profile | High | Moderate to high | Lower, but with higher prices |
| Existing holders | Seed investors, founders | Series A investors join again | Earlier investors plus new late-stage funds |
What Each Round Does to Ownership
Every priced round sells new shares, so existing holders own a smaller percentage afterward. That is equity dilution, and it is the price of the capital. Rounds also often enlarge the employee option pool. How much a round dilutes depends on whether the price is set against pre-money or post-money valuation. A cap table model before each round shows what founders will hold afterward.
If a later round is priced below the previous one, it is a down round, and the protective terms written into earlier series often come into play. Terms from Series A frequently carry forward. Cooley GO warns that Series A terms "can prove difficult to change in subsequent financing rounds", so the first priced round deserves careful legal review.
Key Facts
- Series financing typically runs Series Seed, Series A, Series B, Series C and so on, per Cooley GO.
- Each letter is a separate series of preferred stock, which usually carries a liquidation preference and board-election rights, per Cooley GO.
- Series A money is used for "scaling up" rather than "starting up," and Series A investors are usually venture capital funds, per Cooley GO.
- Series A investors often end up with about 20 to 40 percent ownership, per the same Cooley GO page.
- Round sizes and valuations vary widely by year, sector and company, so check the latest NVCA-PitchBook Venture Monitor edition before benchmarking.
Frequently Asked Questions about Series A, B and C Funding
What do Series A, B and C actually mean?
They name the order of priced equity rounds. Each round sells a new series of preferred stock, so Series A Preferred is the first priced round's stock, Series B Preferred is the next, and so on. The letter is not a measure of size or quality.
What is the difference between Series A and a seed round?
A seed round is usually the earlier, smaller raise, often done on a SAFE or convertible note from angels and small funds. Series A is typically the first institutional round led by a venture fund, priced as a sale of preferred stock, and aimed at scaling what is already working.
Who leads each round?
Series A is usually led by a venture fund. Series B often brings in larger venture or growth funds. Series C and later rounds are commonly led by growth equity, late-stage or crossover investors. These are patterns, not rules.
Is there a Series D, E or F?
Yes. The letters continue as long as a company keeps raising priced rounds. Companies that stay private for years can reach later letters before an IPO or acquisition.
How much do Series A, B and C rounds raise?
It varies by year, sector and company, and published medians shift each quarter and are pulled upward by a few very large deals. For current figures, check the newest NVCA-PitchBook Venture Monitor and compare against companies like yours.
Does every startup need to raise all these rounds?
No. Many companies never raise a Series A, and some raise very little outside capital. A venture path suits businesses that can grow quickly enough to give investors a large return. See bootstrapped vs venture-backed startups for the trade-offs.
Related Reading
