Sean O'Brien
Solo GP · New York, NY
Sean O'Brien is a solo GP based in New York, NY, investing at pre-seed, seed stage. Sean O'Brien's most recent fund with a disclosed size, Alpha Excel Associates LLC - Series I, filed a $4.86M offering with the SEC in Mar 2026. Sean O'Brien has 8 funds and deal vehicles on SEC file, including 1 single-deal SPVs. Estimated typical check: $125K–$400K. Sean O'Brien has dated investing activity in the last 12 months (latest Mar 2026).
Why Sean O'Brien is listed
Named as one of two individuals (Chief Financial Officer of Alpha Partners Management LLC, manager of Issuer) on the Form D for Alpha Excel Associates LLC - Series I, a $4.9M venture fund (Mar 2026) (8 vehicles on file: 7 funds, 1 SPV).
Source: SEC Form D: Alpha Excel Associates LLC - Series I (Mar 26, 2026) · 7 more sources
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- Stages
- Pre-seed, Seed
- Typical check (est.)
- $125K–$400K
- Latest fund
- $4.86M · Mar 2026
- Latest dated activity
- Mar 2026
Is Sean O'Brien a fit for you?
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What does Sean O'Brien invest in?
Sector focus not yet verifiedWhat has Sean O'Brien invested in recently?
- Mar 2026
Alpha Excel Associates LLC - Series I
Invested through a fund
- Dec 2025
KI Opportunities LLC - Series I
Invested through a fund
- Nov 2025
Silvertech Ventures IV LLC - Series I
Invested through a fund
- Nov 2025
Alpha Sentinel Associates LLC
Invested through a fund
- Nov 2025
Interlock Alpha Associates LLC
Invested through a fund
- Sep 2025
Alpha Pathfinder Associates LLC - Series I
Invested through a fund
- Aug 2025
Alpha Zinc Associates LLC
Invested through a fund
Funds and deal vehicles Sean O'Brien filed with the SEC
- Mar 2026
Alpha Excel Associates LLC - Series I
Fund · $4.86M offering
- Dec 2025
KI Opportunities LLC - Series I
Fund · $12.4M offering
- Dec 2025
Alpha Partners Technology Merger SPV LLC
Deal vehicle · $2.12M offering
- Nov 2025
Silvertech Ventures IV LLC - Series I
Fund · $3.73M offering
- Nov 2025
Alpha Sentinel Associates LLC
Fund · $13.4M offering
- Nov 2025
Interlock Alpha Associates LLC
Fund · $12.5M offering
- Sep 2025
Alpha Pathfinder Associates LLC - Series I
Fund · $7.77M offering
- Aug 2025
Alpha Zinc Associates LLC
Fund · $10.5M offering
Sources
- SEC Form D: Alpha Excel Associates LLC - Series IMar 26, 2026
- SEC Form D: KI Opportunities LLC - Series IDec 9, 2025
- SEC Form D: Alpha Partners Technology Merger SPV LLCDec 3, 2025
- SEC Form D: Silvertech Ventures IV LLC - Series INov 26, 2025
- SEC Form D: Alpha Sentinel Associates LLCNov 26, 2025
- SEC Form D: Interlock Alpha Associates LLCNov 26, 2025
- SEC Form D: Alpha Pathfinder Associates LLC - Series ISep 19, 2025
- SEC Form D: Alpha Zinc Associates LLCAug 28, 2025
Data refreshed from public sources Oct 15, 2026. Is this you? Remove or correct this profile.