YC Companies: The Complete Guide to Y Combinator Startups and Their Funding
Everything worth knowing about YC companies in one place: how Y Combinator works, what its portfolio actually builds, and funding benchmarks from 471 verified rounds closed over 20 months, with stage medians, sector shifts, the batch effect, and what it all means for anyone selling to them.
YC companies raise money differently than the rest of the venture market. They raise earlier, they raise faster, and they pull the same small group of investors back to the table round after round.
This guide covers the full picture: how Y Combinator works, which y combinator companies became household names, and what the current portfolio looks like on the ground. It then goes deeper than any directory can, with an analysis of 471 YC backed companies that closed named funding rounds between January 2025 and September 2026.
Every figure in the data sections comes directly from verified funding records, not estimates or third party summaries. If you sell to startups, the benchmarks below tell you who to call, when to call, and what they can afford.
The dataset behind this analysis comes from Fundraise Insider, which tracks newly funded companies every week and delivers a verified sales leads list with C suite contacts, direct emails, and LinkedIn profiles for each one. Static databases show you yc companies months after the money lands.
Fundraise Insider shows you the round the week it closes, when budgets are fresh and decision makers are actively buying. A single one time payment for the Full Stack or Yearbook plan unlocks those weekly leads for life, with no subscription attached.
Table of Contents
- What Is Y Combinator and How the Program Works
- How Many YC Companies Are There?
- Headline Numbers From the YC Portfolio
- Where YC Companies Sit in the Funding Lifecycle
- Round Size Benchmarks by Stage
- Funding Cadence and the Batch Effect
- What YC Startups Actually Build
- The San Francisco Concentration
- Headcount and Time to Capital
- The Investor Network Around Y Combinator
- The Biggest YC Companies by Round Size
- The Most Successful Y Combinator Companies of All Time
- How to Find and Track YC Companies
- How to Sell to Newly Funded YC Startups
- YC Companies: Frequently Asked Questions
- Methodology and Exclusions
Section 1
What Is Y Combinator and How the Program Works
Y Combinator is a startup accelerator founded in 2005 by Paul Graham, Jessica Livingston, Trevor Blackwell, and Robert Morris. It funds early stage companies in batches, runs each batch through a roughly 3 month program, and ends with a demo day where founders present to investors.
The first batch, in the summer of 2005, included Reddit. Two decades later, the accelerator's alumni network is the deepest founder community in technology, and a YC acceptance remains one of the strongest early signals an investor or vendor can read.
The Standard Deal
On its own site, YC states that it invests $500,000 in every company it accepts. The structure is $125,000 for 7 percent on a post money SAFE, plus another $375,000 on an uncapped SAFE with a most favored nation clause.
That deal matters for anyone selling to yc startups, not just founders. It means every company in a new batch starts with meaningful working capital before it raises anything else, so even the youngest batch companies have budget for tools and services.
Four Batches a Year
YC now runs four batches annually: winter, spring, summer, and fall. Each batch pushes a fresh wave of funded companies into the market, which is why YC activity arrives in pulses rather than a steady stream.
Acceptance is highly selective, with thousands of applications competing for a few hundred spots per batch. The companies that get in have been filtered twice by the time you meet them: once by YC partners, and again by the investors who fund them after demo day.
Section 2
How Many YC Companies Are There?
More than 5,000 companies have gone through Y Combinator since 2005, spanning every major sector from payments to fusion energy. The alumni list includes public companies, acquired companies, private giants still compounding, and a long tail of small teams that never broke out.
Counting all of them at once is the wrong frame for most practical questions. The population that matters commercially is much smaller: the yc companies that are actively funded, actively hiring, and actively buying right now.
That active slice is what this report measures. Between January 2025 and September 2026, 471 YC backed companies closed named funding rounds with verifiable details, and they form the dataset for every benchmark below.
The distinction changes how you should use any yc list. A directory tells you a company existed at some point, while a funding record tells you a company has fresh capital and an open buying window today.
Section 3
Headline Numbers From the YC Portfolio
Across the 20 month window, the 471 companies in this yc list raised a combined $13.3 billion in disclosed capital. That figure covers only named rounds with verifiable amounts, from Pre-Seed through Series G.
The portfolio skews young and small. The median company in the dataset employs 14 people, and 208 of the 471 companies, or 44 percent, run with 10 or fewer employees.
Three numbers define the shape of this y combinator companies dataset:
- 358 of 471 companies, or 76 percent, raised at Pre-Seed, Seed, or Series A
- 291 companies, or 62 percent, are headquartered in San Francisco alone
- 300 company descriptions, or 64 percent, reference AI, machine learning, or agents as core to the product
The concentration runs in every direction at once: stage, city, and technology. Understanding it is the fastest way to understand the modern yc portfolio.
Section 4
Where YC Companies Sit in the Funding Lifecycle
Seed is the center of gravity for yc startups. 153 of the 471 companies, 32 percent, closed a Seed round during the window, more than any other stage.
Pre-Seed runs second at 109 companies, lifted by a large wave of fresh batch companies that raised in June 2026. More on that wave in the cadence section below.
Series A and Series B together account for another 150 rounds. Past Series B, the funnel narrows sharply: only 41 companies in the entire dataset raised at Series C through Series G.
That distribution tells you something about the yc portfolio that aggregate valuation headlines hide. The overwhelming majority of y combinator alumni in active fundraising mode are 1 to 4 years old, pre Series B, and still building their first sales and operations stack.
Capital Tells a Different Story Than Count
Count and capital invert. Series A rounds absorbed $3.1 billion, the largest pool of any stage, with a single $1.1 billion round in August 2026 reshaping the total.
Series B followed at $3 billion, then Series C at $2.1 billion and Series D at $1.4 billion. All 109 Pre-Seed rounds combined raised just over $60 million, a rounding error next to the growth stages.
Section 5
Round Size Benchmarks by Stage
These figures come from rounds with disclosed amounts and serve as current benchmarks for anyone evaluating or selling into yc backed companies.
| Stage | Median Round | Middle 50% of Rounds | Top Decile |
|---|---|---|---|
| Pre-Seed | $500K | Sub $1M typical | $1M+ |
| Seed | $4.6M | $3.5M to $6.6M | $10.5M+ |
| Series A | $16M | $13M to $21.5M | $31M+ |
| Series B | $42M | $30M to $60M | $90M+ |
| Series C | $100M | 20 disclosed rounds in window | |
| Series D | $105M | 11 disclosed rounds in window | |
| Series E | $87.5M | 4 disclosed rounds in window | |
The Seed benchmark deserves a closer look because it defines the largest cohort. The median yc startup Seed round landed at $4.6 million, with the middle 50 percent of rounds falling between $3.5 million and $6.6 million.
The top decile of Seed rounds cleared $10.5 million, a figure that would have qualified as a healthy Series A only a few years ago. Stage labels have inflated, and the data confirms it.
Series A and B Benchmarks
Series A rounds for y combinator companies showed a median of $16 million, with the interquartile range spanning $13 million to $21.5 million. The top 10 percent of A rounds reached $31 million or more.
Series B medians hit $42 million, with the middle half of rounds between $30 million and $60 million. A YC company crossing into Series B today is, on capital alone, where Series C companies sat a decade ago.
Section 6
Funding Cadence and the Batch Effect
YC funding does not arrive evenly across the calendar. The quarterly pattern shows 2 pronounced spikes: Q3 2025 with 100 rounds, and Q2 2026 with 115 rounds, the busiest quarter in the dataset.
Both spikes have the same clean explanation. September 2025 produced 57 rounds, 42 of them Pre-Seed checks, and June 2026 topped it with 72 rounds, 50 of them Pre-Seed.
June 2026 remains the single busiest month in the entire dataset. The pattern is consistent with YC batch cycles pushing waves of newly capitalized companies into the market at once.
July 2026 shows the other side of the pulse. The month recorded 20 rounds and not a single Pre-Seed check, the quiet trough that follows each demo day wave before the next batch arrives.
This is the batch effect, and it matters operationally. When a new batch hits demo day, dozens of newly funded y combinator startups enter buying mode within the same 4 to 6 week window.
A closed funding round is one of the strongest event based buying triggers in B2B sales, and the batch effect stacks dozens of those triggers into a single month. Teams that track funding weekly catch that wave as it forms.
Teams that rely on quarterly database refreshes find it after the first vendor decisions are already made. By the time a stale export surfaces a batch company, its stack is often already chosen.
Section 7
What YC Startups Actually Build
Information technology and services dominates the yc company list, accounting for 297 of 471 companies, or 63 percent. Financial services follows at 34 companies, then research at 21, health care at 14, with industrial engineering at 13 and defense and space at 10.
AI Is the Default, Not the Differentiator
300 of the 471 companies, 64 percent, describe AI, machine learning, or autonomous agents as central to their product. Within the most recent cohorts the share runs even higher.
The practical read: AI is no longer a sector inside the YC universe. It is the substrate, and the meaningful differences now show up in which industry the AI is applied to.
Round Sizes Vary Sharply by Sector
Sector choice changes the capital math. Median disclosed rounds by industry vertical:
| Sector | Companies | Median Disclosed Round |
|---|---|---|
| Insurance | 8 | $16M |
| Financial services | 34 | $14.8M |
| Hospital and health care | 14 | $14M |
| Research and biotech adjacent | 21 | $7.2M |
| Defense and space | 10 | $3.8M |
Defense Runs Hot at Both Ends
Defense and space is the clearest read on where YC is leaning next, and the sector now splits into 2 distinct populations. The June 2026 wave brought a fresh crop of Pre-Seed defense entrants, which pulled the sector median down to $3.8 million.
At the other end, the growth stage defense companies raise enormous rounds: Stoke Space at $510 million, Lumen Orbit at $170 million, Turion Space at $75 million, and Hubble Network at $70 million. The pipeline is refilling at the bottom while the top absorbs some of the biggest single checks in the entire yc portfolio.
YC is far from the only source of this activity, and the broader wave is visible in our running list of funded defense tech startups. Vendors that learned to sell into defense primes now have a second, faster moving market in these venture backed entrants.
Section 8
The San Francisco Concentration
The geographic story is concentration without much nuance. San Francisco proper houses 291 of the 471 companies, and California overall holds 331, or 70 percent.
New York is the only meaningful counterweight at 70 companies, 15 percent of the total. Every other metro, including Austin, Los Angeles, and Boston, registers in single digits.
456 of the 471 companies sit in the United States. The remote work thesis that predicted YC dispersion did not survive contact with the AI boom, which has repulled talent and capital into San Francisco at rates that exceed the prior cycle.
For sellers, the YC map mirrors the broader venture map, where our list of funded California startups shows the same gravitational pull. Two metros carry the market, which makes territory planning unusually simple.
Section 9
Headcount and Time to Capital
These are small organizations moving fast. 306 of 471 companies, 65 percent, employ 25 or fewer people, and the median headcount across the full dataset is 14.
The founding to funding gap compresses at the early stages. Companies closing Pre-Seed rounds were a median of 1 year from founding, Seed companies 2 years, Series A companies 3 years, and Series B companies 5 years.
By Series D the median company is 8 years old. The progression maps a consistent rhythm: a yc startup that stays on pace raises roughly every 18 to 24 months through Series B.
Why Headcount Matters for Anyone Selling to These Companies
At 14 employees there is no procurement department, no RFP process, and usually no dedicated buyer for most categories. The founder or a first executive hire makes the purchase decision directly.
That keeps sales cycles short but windows brief. The vendor stack a 14 person company assembles in the 90 days after a round tends to persist for years.
Section 10
The Investor Network Around Y Combinator
The same names appear alongside Y Combinator with striking regularity. Across the 471 companies, the most frequent syndicate partners were:
- Pioneer Fund, appearing in 55 companies
- General Catalyst, 37 companies
- Liquid 2 Ventures, 32 companies
- Andreessen Horowitz, 28 companies
- Alumni Ventures, 25 companies
- Peak XV Partners, 20 companies
- BoxGroup, 19 companies
- Gaingels and Rebel Fund, 18 companies each
- SV Angel, 17 companies
The pattern splits into 2 tiers. Pioneer Fund, Liquid 2 Ventures, Rebel Fund, and Alumni Ventures are YC alumni oriented vehicles that systematically back batch companies at Pre-Seed and Seed.
General Catalyst, Andreessen Horowitz, Sequoia Capital, and Lightspeed Venture Partners enter at Series A and beyond, where they concentrate the larger checks. When one of these firms appears next to Y Combinator on a cap table, the company has typically cleared an external validation bar beyond the batch itself.
Section 11
The Biggest YC Companies by Round Size
The largest verified rounds in the window show how far y combinator alumni travel from their batch origins. Every round below is a named stage with a disclosed amount and date.
Note the composition. Half of the 10 biggest yc companies by round size in this window build physical or regulated products: rockets, fusion reactors, supersonic aircraft, satellites, and public safety hardware.
The stereotype of YC as a pure software accelerator is roughly a decade out of date. The largest single check, a $1.1 billion Series A into AI infrastructure, and the hard tech rounds beneath it both point away from pure application software.
Section 12
The Most Successful Y Combinator Companies of All Time
The biggest y combinator companies in history explain why the accelerator's signal carries so much weight. Several alumni went public, several sold to the largest acquirers in technology, and a handful remain private at enormous scale.
| Company | Status | Known For |
|---|---|---|
| Airbnb | Public | Travel and short term rentals |
| Stripe | Private | Payments infrastructure |
| Coinbase | Public | Cryptocurrency exchange |
| DoorDash | Public | Food delivery |
| Instacart | Public | Grocery delivery |
| Dropbox | Public | Cloud file storage |
| Public | Social platform, first batch alum | |
| GitLab | Public | DevOps platform |
| Twitch | Acquired by Amazon | Live streaming |
| Cruise | Acquired by GM | Autonomous vehicles |
| Rippling | Private | Workforce management software |
| Deel | Private | Global payroll and HR |
| Brex | Private | Corporate cards and finance |
| Gusto | Private | Payroll and benefits |
| Zapier | Private | Workflow automation |
The through line is that nearly all of these companies were once 10 person teams fresh off a batch, buying their first tools and services. The vendors that reached them at that moment grew alongside them.
Several of the names above are still active in our dataset. Rippling, Brex, Flock Safety, and Whatnot all closed major rounds inside the 20 month window, proof that yc companies keep generating buying events long after demo day.
Section 13
How to Find and Track YC Companies
There are three practical ways to build a working list of yc companies, and each fits a different job. The right choice depends on whether you need historical coverage or an active buying signal.
Public Directories
YC maintains a public startup directory of y combinator startups that is searchable by batch, industry, and status. It is the authoritative record of who went through the program, and it costs nothing to browse.
Its limitation is the one every directory shares: it tells you a company exists, not whether it just raised or is currently spending. For research it is excellent, while for pipeline it needs a timing layer on top.
General Prospecting Databases
Platforms like Crunchbase, Apollo, ZoomInfo, and LinkedIn Sales Navigator can filter for YC portfolio companies and append contact data. Our guide to LinkedIn Sales Navigator alternatives breaks down how these platforms compare for startup prospecting.
The tradeoff is freshness. Large databases refresh on their own schedules, so a June batch company may not surface with accurate data until well after its buying window opened.
Weekly Funding Feeds
The third approach is tracking funding events themselves, which is the model Fundraise Insider is built on. Each week it delivers a verified B2B leads list of newly funded companies, including yc startups, with C level names, direct emails, and LinkedIn profiles attached.
Because the trigger is the round rather than the database refresh, the lead arrives while the budget is new. For sellers who care about the batch effect documented above, that gap of weeks is the difference between first call and fifth.
Section 14
How to Sell to Newly Funded YC Startups
The data points to 4 operational conclusions for agencies, SaaS vendors, recruiters, and sales teams targeting yc backed companies.
The volume lives at Pre-Seed through Series A
76 percent of active rounds happen there. The typical newly funded YC company is 10 to 25 people, founder led on purchasing, and assembling its vendor stack right now.
Timing beats targeting
The batch effect concentrates dozens of fresh budgets into narrow windows, and June 2026 was the busiest month yet. The buying decisions made in the 90 days after a round define the stack for years.
The medians give you qualification math
A Seed stage YC company just banked roughly $4.6 million and a Series A company $16 million. That tells you what they can afford before the first call.
Geography simplifies territory planning
San Francisco and New York cover 77 percent of the portfolio. Two metros carry nearly the entire market.
Who to Contact and What to Say
At the stages where most yc startups sit, the buyer is the founder or the first executive hire, not a procurement team. Write to the CEO or the functional lead closest to your category, and keep the pitch anchored to what the new capital is meant to accomplish.
Reference the round without making it the whole message. A note that acknowledges the raise, names a concrete problem that follows it, and proposes a specific next step outperforms generic congratulations.
The mechanics of list building, qualification, and sequencing are covered in our full guide to B2B sales prospecting. The YC specific adjustment is simple: compress every timeline, because these buyers decide in days.
Why Newly Funded Companies Are the Best Accounts on Your List
A company that closed a round last week has fresh budget, board pressure to deploy it, and open decisions across tooling, hiring, and services. A company that raised 2 years ago has none of those conditions working in your favor.
This is why prioritizing newly funded yc companies beats working a larger but colder account list. The same effort, pointed at accounts in an active buying window, produces more meetings and shorter cycles.
Section 15
YC Companies: Frequently Asked Questions
How many YC companies are there?
More than 5,000 companies have gone through Y Combinator since its founding in 2005. Within the most recent 20 months, 471 YC backed companies closed named, verifiable funding rounds, which is the active population measured in this report.
How much does Y Combinator invest in each company?
YC invests $500,000 in every company it accepts. The structure is $125,000 for 7 percent on a post money SAFE plus $375,000 on an uncapped SAFE with a most favored nation clause.
How often does Y Combinator run batches?
YC runs four batches per year: winter, spring, summer, and fall. Each batch ends with a demo day, which pushes a concentrated wave of newly funded companies into the market at once.
What share of YC startups are AI companies?
In this dataset, 300 of 471 companies, or 64 percent, describe AI, machine learning, or autonomous agents as core to their product. In the newest cohorts the share runs even higher.
What is the median Seed round for a YC company?
The median Seed round for yc companies in this window was $4.6 million, with the middle 50 percent of rounds between $3.5 million and $6.6 million. Series A medians reached $16 million and Series B medians hit $42 million.
Where are most YC companies located?
San Francisco alone houses 62 percent of the companies in this dataset, and California overall holds 70 percent. New York City is the only other meaningful hub at 15 percent.
When is the best time to pitch a YC startup?
The strongest window is the first 90 days after a funding round closes, when budget is fresh and the vendor stack is still open. Batch cycles concentrate these windows, so demo day months like June 2026 produce dozens of open buying windows simultaneously.
Are YC companies good B2B prospects?
Yes, provided you reach them early. They are small, founder led, and fast to decide, with a median headcount of 14 and no procurement layer, so the vendor that arrives first with a relevant offer usually wins the category.
Reach YC Companies the Week Their Round Closes
Apollo and ZoomInfo can tell you a company exists. Fundraise Insider tells you the week its buying window opened, with verified C suite emails and LinkedIn URLs for newly funded yc companies and thousands of other funded startups, delivered every week.
Choose Full Stack at $149 or Yearbook at $299. Both are one time payments that deliver weekly verified leads for life.
See Plans and PricingOne time payment. Weekly leads for life. No subscription.
Appendix
Methodology and Exclusions
This analysis draws on Fundraise Insider weekly funding records covering January 2025 through September 2026. YC backed companies were identified through investor attribution naming Y Combinator among each company's top investors.
Each company is counted once, by its most recent round in the window. Figures therefore describe last known rounds and do not represent cumulative capital raised by each company over its lifetime.
Program facts in Sections 1 and 2, including the standard deal and batch cadence, come from Y Combinator's own published materials. All time company outcomes in Section 12 reflect widely documented public events such as IPOs and acquisitions.