# Startup funding, week of 17 August: River AI's $1.1B Series A leads 54 rounds

> We read 54 equity rounds announced from 17 August to 23 August 2026, raising $4.5B between them.

Source: https://millionrounds.com/news/weekly/2026-08-17 (Millionrounds; every figure on the page links to its filing or article)

Equity rounds **54** announced this week, 51 with an amount

Raised **$4.5B** across those rounds

Lead named **78%** of rounds say who led

Countries **18** where this week's rounds were raised

## The biggest rounds

- [1 **River AI** Series A · United States · led by General Catalyst, AMP PBC **$1.1B**](https://millionrounds.com/company/river-ai)
- [2 **Castelion** Series C · United States · led by Andreessen Horowitz, JP Morgan Chase **$800M**](https://millionrounds.com/company/castelion)
- [3 **Higgsfield** Series B · United States · led by DST Global **$400M**](https://millionrounds.com/company/higgsfield)
- [4 **Groq** Series A · United States · led by Disruptive **$350M**](https://millionrounds.com/company/groq)
- [5 W **Wispr** Series B · United States · led by Menlo Ventures **$280M**](https://millionrounds.com/company/wispr)
- [6 **Starcloud** Series A · United States · led by Manhattan West **$250M**](https://millionrounds.com/company/starcloud)
- [7 **Muon Space** Series C · United States · led by Eclipse Capital **$250M**](https://millionrounds.com/company/muon-space)
- [8 **Gravis Robotics** Series A · Switzerland · led by SoftBank BB Corp **$200M**](https://millionrounds.com/company/gravis-robotics)
- [9 **Also** Series D · United States · led by Prysm Capital **$150M**](https://millionrounds.com/company/also)
- [10 **Velaura AI** Series A · United States · led by Seligman Ventures **$110M**](https://millionrounds.com/company/velaura-ai)

## By stage, against the year

Each stage's median this week beside its median over the last twelve months. A single week is a small sample, so read the gap as a hint, not a trend.

[Pre-seed](https://millionrounds.com/benchmarks/pre-seed) *9* **$1.2M** this week **$2.0M** 12-month median

[Seed](https://millionrounds.com/benchmarks/seed) *17* **$7.9M** this week **$5.5M** 12-month median

[Series A](https://millionrounds.com/benchmarks/series-a) *13* **$25M** this week **$20M** 12-month median

[Series B](https://millionrounds.com/benchmarks/series-b) *5* **$61M** this week **$50M** 12-month median

[Series C](https://millionrounds.com/benchmarks/series-c) *2* **$525M** this week **$100M** 12-month median

[Series D](https://millionrounds.com/benchmarks/series-d) *3* **$33M** this week **$158M** 12-month median

[Growth](https://millionrounds.com/benchmarks/growth) *5* **$24M** this week **$108M** 12-month median

## The most active leads

Firms that led two or more of the week's rounds.

- [**Battery Ventures** Flash, Rundoo *2 led*](https://millionrounds.com/fund/battery-ventures)

## Where

- United States **21**
- Canada **8**
- United Kingdom **5**
- Australia **4**
- Germany **1**
- Chile **1**

United States had the most rounds this week.

## In what

- AI **26**
- Software **7**
- Construction **7**
- Healthcare **5**
- Cloud **5**
- Defence Tech **5**
- Big Data & Analytics **4**
- Cybersecurity **4**

AI was the busiest sector.

**How this roundup is made**

It is written from the rounds we read that week in named articles and filings. Only equity rounds with a stage count towards the figures; debt, grants and public companies' raises do not. We read more sources every month, so the number of rounds says more about our coverage than about the market: compare medians, not totals. [How we read rounds](https://millionrounds.com/methodology) · [Report a mistake](https://millionrounds.com/corrections)