Y Combinator leads with 22 companies, a16z hits a record high—A thorough analysis of the top VC players active in April

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Despite the start of the new fiscal year, the U.S. startup investment market saw a slightly sluggish number of funding deals in April. While major venture capital (VC) firms, in particular, continued to narrow down their investment targets—a move that has become standard—their participation in umbrella funds and large-scale rounds was notable. This article highlights the "most active" U.S. startup investment firms in April 2025 and provides a concrete breakdown of each firm's deal count and representative investment cases.

1. Andreessen Horowitz’s surge

1-1. Trends in deal count

Menlo Park-based major VC Andreessen Horowitz (commonly known as a16z) closed 13 deals in April, marking its highest monthly investment count since January. While it is not unusual for this firm to top the list in terms of deal volume, this activity shows no signs of "downtime" amidst the early spring slowdown in investment sentiment.

1-2. Representative lead investment cases

• Base Power(Series B, approx. $200 million)
  An Austin, Texas-based residential backup power system company. It features battery solutions that charge during off-peak electricity hours and was co-led by Addition, Lightspeed, and Valor.

• Flow(Founded by Adam Neumann / over $100 million)
  A residential real estate startup by WeWork co-founder Adam Neumann. The valuation for the series round is reported to be approximately $2.5 billion (according to Bloomberg).

2. Khosla Ventures’s resurgence

2-1. Deal count and historical comparison

Khosla Ventures executed 10 investments in April, marking its highest monthly count since April 2024. While other firms have shifted to a "wait-and-see" approach, their active capital deployment stands out.

2-2. Notable deals

• Science ($104 million round)
  A biotech company founded by a former Neuralink co-founder. It is pursuing next-generation medicine in both brain implants and retinal implants.

• Cyberhaven (Series D, $100 million)
  Provides a data detection and response platform and has reached a unicorn valuation ($1 billion).

• Mainspring Energy (Series F, $258 million)
  A generator manufacturer. This was a large-scale round driven by the expansion of power demand accompanying the rise in AI computational needs.

3. General Catalyst’s strategic adjustment

3-1. Changes in investment pace

General Catalyst slowed its pace from 26 deals in February-March to just 9 in April. Although it was its "slowest month" since January, the deals it participated in were diverse in both scale and sector.

3-2. Lead deals and small follow-on deals

• Mainspring Energy (Series F)
  Led the aforementioned large-scale round. Their bet on the environment and energy sector continues.

• Vivere Partners (Specialty Insurance)

• Fourier (Green Hydrogen Energy)

4. Other Notable Firms

4-1. BoxGroup and Index Ventures

Both firms completed 8 investments. At the seed to Series A stages, we see scattered deals targeting the forefront of unique domains.

4-2. Ocampo Capital

In April, they achieved the highest number of lead investments with 7 lead/co-lead deals. This firm has a strength in small-to-medium-scale hands-on deals.

4-3. Greenoaks Capital Partners

They led the $2 billion mega-round for Safe Superintelligence (at a $32 billion valuation), reigning at the top in terms of dollar amount. Their commitment to large-scale tech rounds stands out.

4-4. Y Combinator

By investing in 22 companies, they remained the leader in April as an accelerator/incubator. They once again demonstrated their broad reach at the early stage.

5. Future Outlook

While some view the stagnation in fundraising at the start of spring as temporary, it is clear that investors are proceeding with selection and concentration toward "high-quality deals." In particular, attention remains high for unicorn candidates in energy, biotech, and infrastructure, and the "winners of early investment" will likely emerge during the market recovery phase from summer onwards. With this in mind, please stay tuned for our next report on May's trends.

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