# Jimmy Vaiopoulos

> Jimmy Vaiopoulos is a private equity investor at Stack Capital backing Energy and CleanTech. See 1 investments, check sizes, portfolio. Updated Aug 2026.

- Type: Angel Investor
- Fund: [Stack Capital](https://shizune.co/investors/profile/stack-capital)
- Total investments: 1
- Lead investor: 100%
- Last updated: Aug 2026
- LinkedIn: https://ca.linkedin.com/in/jimmyvaiopoulos
- X (Twitter): https://twitter.com/JimVaio
- Website: https://www.stackcapitalgroup.com/

Jimmy Vaiopoulos is a private equity investor at Stack Capital focused on Energy and CleanTech. Jimmy Vaiopoulos - Co-founder and CFO @ Stack Capital

## Investment focus

### Industry

| Industry | Investments | Share |
| --- | --- | --- |
| Energy | 1 | 100% |
| CleanTech | 1 | 100% |
| Clean Energy | 1 | 100% |
| Renewable Energy | 1 | 100% |

## Investments

| Company | Description | Amount | Stage | Date | Website |
| --- | --- | --- | --- | --- | --- |
| X-energy | X-Energy is a nuclear reactor and fuel design engineering company that develops Generation IV, high-temperature gas-cooled small modular reactors (SMRs) together with proprietary TRISO-X particle fuel. Their flagship reactor, the Xe-100, delivers about 80 MWe per unit and can be scaled in modular “packs” to reach higher output. X-Energy also buildsits own TRISO-X fuel to maintain supply control and quality. In addition, the company operates a plant support center to provide fleet monitoring, maintenance planning, training, and diagnostics for its reactor customers. | $5M | Private Equity |  |  |

1 of 1 investments shown.

## About Stack Capital

VC Fund · Toronto, Canada

Stack Capital Group offers long-term growth potential to innovative growth and late-stage private companies. It has the ability to invest in private companies from various sectors before they go public, as well as hold them as public companies.

4 contacts available at Stack Capital.

| Name | Title | Profile |
| --- | --- | --- |
| Jimmy Vaiopoulos | Co-founder and CFO | https://shizune.co/investors/profile/jimmy-vaiopoulos-332b |
| Brian Viveiros | Co-Founder / VP, Corporate Development & Investor Relations | https://shizune.co/investors/profile/brian-viveiros-652b |
| Jason Meiers | CIO&Co-Founder | https://shizune.co/investors/profile/jason-meiers-0954 |
| Jeff Parks | Co-Founder - CEO | https://shizune.co/investors/profile/jeff-parks-0947 |

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## FAQ

### What does Jimmy Vaiopoulos invest in?

Jimmy Vaiopoulos invests primarily in Energy, CleanTech and Clean Energy startups, most often at Private Equity stage. Most of the 1 investments tracked by Shizune back companies in United States. The Investment Focus section breaks down every industry, stage and country in the portfolio.

### Is Shizune's investor data accurate?

Yes — every stat on this profile is calculated from confirmed public funding rounds monitored across hundreds of sources since 2020. This profile was last refreshed in Aug 2026 and is updated monthly. Spotted something off? Use the “Suggest an edit” link near the top of the page.

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