MUUS & Company is the private holding company and family office of Tiger 21 founder Michael Sonnenfeldt, founded in 1998. Its dedicated climate tech venture arm, MUUS Climate Partners, invests at the convergence of decarbonization and technological innovation, with its latest Convergence Fund II closing at $50 million.
50% of their portfolio is in Climate & Energy. They made 1 investment in the last 12 months. Their most common stage is series-a (40% of deals). Average disclosed round size is $57.5M (across 9 rounds with reported amounts).
Portfolio
9
Fund Size
$50M
Top Stage
Series A
Last 12 Mo
1
Team
Laura DiBonaventura
PRINCIPAL, CLIMATE INVESTMENTS
Isaac Sonnenfeldt
ASSOCIATE
Dominique Pierro
ADMINISTRATIVE MANAGER
Mary Beth Bruggeman
PHILANTHROPIC ADVISOR
Michael W. Sonnenfeldt
FOUNDER AND CHAIRMAN
Portfolio Breakdown
Stage Distribution
Sector Distribution
Investment Activity
Portfolio
| Company | Round | Amount | Date |
|---|---|---|---|
| SSensera Systems | Series B | $27M | Feb 2026 |
 Aepnus | Seed | $8M | Jun 2024 |
 Ivy Energy | Series A | $18M | Apr 2024 |
 BrightNight | Unknown | $440M | Jan 2024 |
 Harvest Thermal | Seed | $2.5M | Oct 2023 |
| SSensera Systems | Series A | — | Aug 2023 |
 Energetic Insurance | Series A | $2.5M | — |
 Amperon | Series A | $7M | — |
 Cache Energy | Seed | $8.5M | — |
 RailVision | Seed | $4M | — |
Top Co-Investors
Last updated: 27 September 2026