Firms
S3 Ventures
S3 Ventures is an Austin-based venture-capital firm founded in 2005 by Brian R. Smith, investing in seed, Series A and Series B business-technology and health-care-technology companies nationwide. Its portfolio spans enterprise AI, automation, AI computing and quantum technology as well as medical devices and neurological assessment, including BrainCheck and stroke-intervention developer RapidPulse. The firm is backed by a single philanthropic family limited partner and emphasizes patient capital and operational support. Its announced $1 billion-plus assets under management and aggregate portfolio-company fundraising are distinct from individual fund closes. S3 announced a $250 million seventh fund in 2022 and a $250 million eighth fund in December 2025; these public fund announcements do not establish that every commitment had been paid or an exact legal closing day. The current public directory identifies eleven staff. Charlie Plauche is labeled Managing Director in that directory and General Partner in his individual biography, a source discrepancy retained explicitly. The unrelated s3venture.com advertising business is excluded.
- Founded
- 2005
- Type
- Venture capital
Funds6
Team
Operations and support
 Aaron PermanGeneral Partner |
 Anthony MarfisiAssociate |
 Brian R. SmithManaging Director |
 Charlie PlaucheManaging Director (team directory); General Partner (individual biography) |
 Eric EngineerGeneral Partner |
 Joe CurryPrincipal |
 Kathryn DeebelDirector of Platform & Network |
 Kevin HaleyAssociate |
 Nicole BentzVice President |
 Shelley GravesController |
 Will OmbergSenior Associate |
Co-investing
Next Coast Ventures
BrainCheck$13M · 2026-02-26- BrainCheck$15M · 2024-03-06
- BrainCheck$10M · 2021-11-03
Tensility Venture Partners- BrainCheck$10M · 2021-11-03
- BrainCheck$8M · Unknown date
- BrainCheck$— · Unknown date
True Wealth Ventures- BrainCheck$10M · 2021-11-03
- BrainCheck$8M · Unknown date
- BrainCheck$— · Unknown date
UPMC Enterprises- BrainCheck$13M · 2026-02-26
- BrainCheck$15M · 2024-03-06
- BrainCheck$10M · 2021-11-03
- BrainCheck$10M · 2021-11-03
- BrainCheck$8M · Unknown date
Arpio$8M · Unknown date
- Arpio$15M · Unknown date
- Arpio$15M · Unknown date
PSL Ventures
Kamiwaza$8M · Unknown date
- Arpio$8M · Unknown date
- BrainCheck$— · Unknown date
Investments
| $13M2026-02-26 | BrainCheck | Next Coast Ventures, S3 Ventures, UPMC Enterprises |
| $15M2024-03-06 | BrainCheck | Next Coast Ventures, S3 Ventures, UPMC Enterprises |
| $10M2021-11-03 | BrainCheck | Next Coast Ventures, S3 Ventures, Nueterra Capital, UPMC Enterprises, True Wealth Ventures, Tensility Venture Partners |
| $10M2010 |  Sipera | Sequoia, S3 Ventures |
| $8MUnknown date | Kamiwaza | S3 Ventures, PSL Ventures |
| $8MUnknown date | BrainCheck | S3 Ventures, Tensility Venture Partners, Nueterra Capital, True Wealth Ventures |
| $—Unknown date | BrainCheck | True Wealth Ventures, S3 Ventures, XFactor Ventures, Tensility Venture Partners |
| $15MUnknown date | Arpio | Y Combinator, Paladin Capital Group, Valor Equity Partners, Uncorrelated Ventures, S3 Ventures, Lookout Ventures |
| $8MUnknown date | Arpio | Y Combinator, Valor Equity Partners, Uncorrelated Ventures, S3 Ventures, Companyon Ventures, Triangle Tweener Fund |