DiamondStream Partners
Investment firm; participated in Elroy Air's January 2025 funding round.
DiamondStream Partners (diamondstream.com) is a Seattle, WA-based venture firm co-founded by William Dean Donovan and Brian Charles Flynn, Jr., making thematic investments in aerial and related mobility businesses. It describes its approach as looking 'for the rough diamonds in mobility transformation that we can help founders transform into fully cut gems,' targeting middle-stage next-generation-transportation companies — particularly electrically powered aircraft substituting for car/truck trips — and favoring 'market stimulation' bets with near-term prospects in existing markets and long-term upside as adjacent use cases emerge. Donovan, also a co-founder of Volaris (Mexico's largest airline, NYSE-listed since 2013), sits on the boards of several portfolio companies including Elroy Air, JetZero, Wingtra, and Volantio.
Overview
- Firm
- DiamondStream Partners
- Headquarters
- Seattle, WA
- Founded
- 2003
- AUM
- Stages
- Growth
- Thesis
- DiamondStream Partners (diamondstream.com) is a Seattle, WA-based venture firm co-founded by William Dean Donovan and Brian Charles Flynn, Jr., making thematic investments in aerial and related mobility businesses. It describes its approach as looking 'for the rough diamonds in mobility transformation that we can help founders transform into fully cut gems,' targeting middle-stage companies developing next-generation transportation — particularly electrically powered aircraft substituting for car/truck trips — and favoring 'market stimulation' bets on technologies with near-term prospects in existing markets and long-term upside as adjacent use cases emerge. Donovan, also a co-founder of Volaris (Mexico's largest airline, NYSE-listed since 2013), sits on the boards of several portfolio companies including Elroy Air, JetZero, Wingtra, and Volantio.
Portfolio companies1
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Frequently asked
- What is DiamondStream Partners?
- DiamondStream Partners (diamondstream.com) is a Seattle, WA-based venture firm co-founded by William Dean Donovan and Brian Charles Flynn, Jr., making thematic investments in aerial and related mobility businesses. It describes its approach as looking 'for the rough diamonds in mobility transformation that we can help founders transform into fully cut gems,' targeting middle-stage companies developing next-generation transportation — particularly electrically powered aircraft substituting for car/truck trips — and favoring 'market stimulation' bets on technologies with near-term prospects in existing markets and long-term upside as adjacent use cases emerge. Donovan, also a co-founder of Volaris (Mexico's largest airline, NYSE-listed since 2013), sits on the boards of several portfolio companies including Elroy Air, JetZero, Wingtra, and Volantio.
- What stages does DiamondStream Partners invest at?
- DiamondStream Partners invests at Growth.
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Sources & citations2
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- 1
DiamondStream Partners is a Seattle-based venture firm making thematic investments in aerial mobility, co-founded by William Dean Donovan and Brian Charles Flynn, Jr.
DiamondStream Partners: About / Team pageVerified2026-08-08 - 2
DiamondStream Partners participated in Elroy Air's January 2025 funding round, alongside Marlinspike Partners, Shield Capital, Snowpoint Ventures, Lockheed Martin Ventures, Milano Investment Partners, and Levitate Capital.
Elroy Air: Elroy Air Brings on Dr. Andrew Clare as CEO and Secures Additional Funding to Scale BusinessVerified2025-01-14