Definitive YC Companies' Guide: Funding Patterns Across Y Combinator Startups
A data analysis of every verified, named funding round closed by YC backed companies over 17 months: stage benchmarks, sector shifts, the batch effect, and what it all means for anyone selling to them.
Y Combinator 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 report analyzes 377 YC backed companies that closed named funding rounds between January 2025 and June 2026. Every figure below comes directly from verified funding records, not estimates or third party summaries.
The dataset behind this analysis comes from Fundraise Insider, which tracks newly funded companies every week and delivers verified 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. If you sell to funded startups, that timing gap is the entire game.
Table of Contents
- 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 YC
- The Biggest YC Companies by Round Size
- What This Means If You Sell to YC Startups
- Methodology and Exclusions
Section 1
Headline Numbers From the YC Portfolio
Across the 17 month window, the 377 companies in this yc list raised a combined $10.5 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 17 people, and 151 of the 377 companies, exactly 40 percent, run with 10 or fewer employees.
Three numbers define the shape of this y combinator companies dataset:
- 277 of 377 companies, or 73 percent, raised at Pre-Seed, Seed, or Series A
- 231 companies, or 61 percent, are headquartered in San Francisco alone
- 231 company descriptions, also 61 percent, reference AI, machine learning, or agents as core to the product
The overlap of those last 2 figures is coincidence. The concentration behind them is not.
Section 2
Where YC Companies Sit in the Funding Lifecycle
Seed is the center of gravity for yc startups. 137 of the 377 companies, just over 36 percent, closed a Seed round during the window, more than any other stage by a wide margin.
Series A and Series B together account for another 134 rounds. Past Series B, the funnel narrows sharply: only 35 companies in the entire dataset raised at Series C or later.
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 2 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 B rounds, only 14 percent of deals, absorbed $2.9 billion, the largest pool of any stage.
Series A followed at $1.8 billion, then Series C at $1.2 billion and Series D at $1.1 billion. All Pre-Seed rounds combined raised under $37 million, a rounding error next to the growth stages.
Section 3
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 | $4.5M | $3.4M to $6.3M | $8.8M+ |
| Series A | $16M | $12.2M to $21M | $30M+ |
| Series B | $44M | $30.5M to $67.5M | $100M+ |
| Series C | $70M | 16 rounds in window | |
| Series D | $80M | 9 rounds in window | |
| Series E | $96M | 5 rounds in window | |
The Seed benchmark deserves a closer look because it defines the largest cohort. The median yc startup Seed round landed at $4.5 million, with the middle 50 percent of rounds falling between $3.4 million and $6.3 million.
The top decile of Seed rounds cleared $8.8 million, which would have qualified as a 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 $12.2 million to $21 million. The top 10 percent of A rounds reached $30 million or more.
Series B medians hit $44 million, with the middle half of rounds between $30.5 million and $67.5 million. A YC company crossing into Series B today is, on capital alone, where Series C companies sat a decade ago.
Section 4
Funding Cadence and the Batch Effect
YC funding does not arrive evenly across the calendar. The quarterly pattern shows a pronounced spike in Q3 2025, when 110 companies closed rounds, more than double the volume of either of the first 2 quarters.
The spike has a clean explanation. September 2025 alone produced 65 rounds, and 42 of them were Pre-Seed checks, consistent with a YC batch cycle pushing a wave of new companies into the market at once.
This is the batch effect, and it matters operationally. When a combinator latest batch hits demo day, dozens of newly capitalized companies enter buying mode within the same 4 to 6 week window.
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.
Section 5
What YC Startups Actually Build
Information technology and services dominates the yc company list, accounting for 244 of 377 companies, or 65 percent. Financial services follows at 26 companies, then research at 18, hospital and health care at 10, and defense and space at 9.
AI Is the Default, Not the Differentiator
231 of the 377 companies, 61 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 |
|---|---|---|
| Defense and space | 9 | $39.4M |
| Insurance | 7 | $25M |
| Financial services | 26 | $20.3M |
| Hospital and health care | 10 | $14M |
| Research and biotech adjacent | 18 | $7.2M |
Defense stands out. Y Combinator has visibly leaned into defense and hard tech, and the 9 defense and space companies in this dataset raised at medians nearly 9 times the typical Seed round.
For anyone watching where combinator seeks startups in defense, the capital intensity confirms the thesis. These companies raise bigger, earlier, because hardware and clearance timelines demand it.
Section 6
The San Francisco Concentration
The geographic story is concentration without much nuance. San Francisco proper houses 231 of the 377 companies, and California overall holds 261, or 69 percent.
New York is the only meaningful counterweight at 61 companies, 16 percent of the total. Every other metro, including Austin, Los Angeles, and Boston, registers in single digits.
367 of the 377 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.
Section 7
Headcount and Time to Capital
These are small organizations moving fast. 228 of 377 companies, 60 percent, employ 25 or fewer people, and the median headcount across the full dataset is 17.
The founding to funding gap compresses at the early stages. Companies closing Seed rounds were a median of 2 years from founding, Series A companies 3 years, and Series B companies 5 years.
By Series D the median company is 9 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 17 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 17 person company assembles in the 90 days after a round tends to persist for years.
Section 8
The Investor Network Around Y Combinator
The same names appear alongside Y Combinator with striking regularity. Across the 377 companies, the most frequent syndicate partners were:
- Pioneer Fund, appearing in 47 companies
- General Catalyst, 35 companies
- Liquid 2 Ventures, 30 companies
- Andreessen Horowitz, 24 companies
- Alumni Ventures, 23 companies
- Gaingels and Rebel Fund, 17 companies each
- Peak XV Partners, 16 companies
- BoxGroup and SV Angel, 15 companies each
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 9
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 capital flows now run through hard tech.
Section 10
What This Means If You Sell to 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 Seed and Series A
73 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. 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 $4.5 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.
Reach YC Founders the Week Their Round Closes
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Appendix
Methodology and Exclusions
This analysis draws on Fundraise Insider weekly funding records covering January 2025 through early June 2026. YC backed companies were identified through investor attribution naming Y Combinator among each company's top investors.
The raw extract contained 420 companies. Records were excluded where the funding type was unnamed or undisclosed, and 1 record was removed for a funding amount inconsistent with any verifiable public round.
The final dataset contains 377 companies with named stages. 364 disclosed a nonzero round amount, while 7 reported zero values and 6 reported no amount, all of which were excluded from amount based calculations.
Records before 2025 lack investor attribution in the source data and fall outside this report. Figures describe last known rounds within the window and do not represent cumulative capital raised by each company over its lifetime.