SUM Ventures Research
Investment Thesis
SUM Ventures is an early-stage, generalist venture firm that describes its approach as "earn conviction, concentrate behind winners." It builds a broad portfolio at seed with smaller first checks, then concentrates capital as founders execute. The site says roughly 80% of capital ultimately goes into the top third of the portfolio. The firm argues that small seed funds (under $50M) and emerging managers structurally outperform larger, established funds on TVPI, IRR and DPI, and positions itself as a carry-driven, right-sized-capital investor that does not want founders overcapitalized early.
Stage Focus
Seed is the core entry point, with pre-seed in the mix per third-party descriptions. SUM uses a phased approach: enter early with a small check, then earn the right to invest more through follow-ons in later rounds. Several companies carry Fund I, II and III exposure (Brius, PayAmigo, Automotus, ClearClub, UNest, FantasyLife), which shows the follow-on discipline in practice. Fund II was launched as the "Inflection Fund" to double down on the highest-conviction Fund I positions.
Check Size
The website does not publish a check size range, so none is recorded. The firm says it deployed more than $600M of follow-on capital into portfolio companies after its first check, which reflects rounds it helped fill rather than its own checks.
Lead Tendency
The site says SUM has followed 53 funds as first investors and works with angel networks and LP co-investors. It also offers LPs SPV co-investment. Whether SUM leads rounds is not stated on the pages read, so lead tendency is recorded as unknown.
Recent Activity
The firm is actively deploying from Fund III. Fund III investments announced on its news page include AssistMe (Berlin, care-home digitalization), greenLi (lithium extraction), Red Ace Bio (oncology), and Root (community platform). Fund III follow-ons include PayAmigo and Purlin. Other Fund III names on the portfolio page include Transparency Analytics (private credit ratings), Purple Rhombus (defense UAS), Wilder Industries (aerospace robotics), Circularity Fuels (sustainable aviation fuel), Hellbender (edge computing for defense), Rightview AI, Odva, Vectorial, Nuvola Technology and Product Society. The contact page says the firm is currently raising and deploying from Fund III.
Portfolio Highlights
The portfolio page lists 49 companies across Funds I, II and III. Notable names include Acorns (micro-investing), Brius (orthodontics), Automotus (computer-vision curb management, $9M Series A), PlantSwitch (plant-based resin, $17M Series A, introduced to Siemens for a debt facility), Irrigreen ($19M Series A), GeCKo Materials ($8M seed), FantasyLife ($7M seed), HyperSpectral ($7M Series A-2) and Breakr. The first Fund I exit was LiveEasy, acquired by AppFolio in October 2024. The site claims $18B+ in combined team exit value and top-decile DPI, TVPI and net IRR for Funds I and II (2022 and 2023 vintages), which are the firm's own claims.
Team
- Garrett Gilbertson, Managing Partner: chairman of Band of Angels Los Angeles, former USAF Captain, prior investing for family offices, angel groups and corporate venture funds.
- Harry Hopper, Senior Partner: former Managing Partner at Columbia Capital across four institutional funds ($2B+).
- Raj Khoshoo, Senior Partner: retired SVP Strategic Alliances at Siemens Digital Industries Software, led roughly $8B of M&A planning.
- Derek Hu, Partner: co-founder and Managing Partner of TFA International family fund.
- Brent Celek, Partner: former Philadelphia Eagles tight end and Super Bowl LII champion.
- Brian Stephenson, Partner.
- Venture partners: Peter Jun, Nachi Gupta (physician-scientist, Chief Innovation Officer at Kriya Therapeutics), Margot Shapiro, Chris Sporck (battery management, Monolithic Power Systems), Rick Lu (aerospace and defense founder), Tammo Mueller (Quantiva).
Decision Process
The decision process is not described on the pages read. The firm is run by a partner group with a broad venture-partner bench that supplies sector expertise, and it uses an AI underwriting tool called Enverite. It is recorded as a partnership.
Founder Preferences
The site stresses visionary founders, and says 38% of portfolio companies have women founders and 50% have immigrant founders. It favors founders who show real execution over early vision, and keeps rounds disciplined. Founders also get introductions to corporates (the Siemens example), operator and angel networks, and a monthly LP and angel investor meeting.
Geographic Focus
The firm appears to be based in the Los Angeles area (Santa Monica per a third-party listing). The portfolio is US-centered, with international companies including AssistMe (Berlin), Oze (Africa), PayAmigo (Latin America) and PlantSwitch (manufacturing in China and the US). The site describes itself as generalist and not geography-limited.
Sourcing
SUM sponsors Pepperdine's Most Fundable Companies and is affiliated with Band of Angels. Leaders from four angel networks and five venture funds are LPs, which feeds shared deal flow and co-investment. The firm accepts pitches through sum.vc/pitch.