Big round · 21 September 2026

Rainmaker raises $100M Series B

By Millionrounds ResearchPublished 22 September 2026Updated 27 September 2026

Rainmaker, based in United States, has raised $100M in a Series B, announced on 21 September 2026. 7 other investors joined. It is the 444th largest equity round we recorded in the twelve months to that date, and the 89th largest Series B of 393. The median Series B over the same period was $50M, so this one is 2.0 times that. Its previous round on record was a Series A of $25M in May 2025, 17 months earlier.

Raised$100M3 sources reported it
StageSeries B2 earlier rounds on record
Investors7no lead named
Where USUnited States

Climate TechWater

How big is it?

Against every equity round we recorded in the twelve months to 21 September 2026. Ranks count companies, so the same raise reported twice is counted once.

#444equity round of the last twelve months
#89Series B of 393 in that time
#286round in United States, of 1,129
This round$100M
Median Series B$50M

2.0 times the median Series B of the last twelve months.

Who invested

In the round

Funding history

  1. September 2026Series B$100M
  2. May 2025Series A$25M
  3. April 2023Pre-seed$500K

$126M raised across the 3 rounds we hold.

Reported by

  1. TechStartups21 September
  2. Ventureburn21 September
  3. AlleyWatch27 September

The round's figures come from these reports; each link opens the original.

Other big rounds that week

Island$400M Series FBasecamp Research$140M Series CVVerda$189M Series BAngle Health$600M Series C
The companyRainmaker on Millionrounds→Weekly roundupWeek of 21 September→Monthly roundupSeptember 2026→