Principal Investments Intern 4 to 8 month Internship

Posted on 10/30/2025

Castleton Commodities International

Castleton Commodities International

No salary listed

London, UK

In Person

Application Deadline: 5 January 2026 at 12 pm GMT

The European Power Principal Investments team is hiring an Intern in London to support our continued growth. This is an opportunity to learn from a preeminent investment team with a strong track record and a substantial capital deployment agenda across the energy transition, decarbonization of hard-to-abate industries, and the build‑out of digital infrastructure. We operate with a flexible, opportunistic mandate—unconstrained by rigid investment guidelines—allowing us to invest across the capital structure, ownership levels, and stages of development. 

Why this internship: 

  • Meaningful responsibility from day one on live deals and active portfolio assets 
  • Direct mentorship and daily exposure to senior team members 
  • Broad, end-to-end deal experience across origination, execution, and ownership 
  • Opportunity to contribute to the energy transition at scale across European markets 
  • Collaborative culture that values curiosity, initiative, and excellence 

What you’ll do: 

  • Work alongside senior members of the Principal Investment to originate and execute investment opportunities across Europe 
  • Support the full investment lifecycle: market research, M&A valuation, due diligence, deal execution, financing/refinancing, and portfolio management 
  • Build and refine financial models to evaluate equity and debt opportunities, informing real investment decisions 
  • Prepare materials for investment committee and board approvals, pre- and post-investment 
  • Analyze complex financial, commercial, and power market data to develop and stress-test investment theses 
  • Track market trends, policy developments, and competitive dynamics to inform strategy 
  • Collaborate with trading, risk, legal, and operations to ensure timely and robust transaction execution 
  • Coordinate with external advisors such as consultants, lenders, legal, etc.  
  • Maintain and enhance internal databases and market intelligence 

What you’ll learn 

  • Best-in-class financial modeling and valuation in real-world scenarios 
  • How investors assess risk/return, structure deals, and create value 
  • Power markets fundamentals and the evolving European energy transition landscape 
  • How to communicate insights succinctly to senior stakeholders and investment committees 

Qualifications 

  • Currently pursuing a degree in finance, economics, mathematics, engineering, or a related field; other disciplines considered with demonstrable corporate finance experience 
  • Target graduation between Spring 2027 and Fall 2027 (available for full-time roles by end of September 2027) 
  • Strong financial modeling, analytical, and quantitative skills 
  • Clear and concise communication skills—written, verbal, and presentation 
  • High initiative, ownership mindset, and comfort working in a lean, fast-paced team 
  • Genuine interest in investing, the energy transition, and European power markets 
  • Prior experience in private equity, investment banking, or corporate finance is a plus, not a requirement 
  • Proficiency in a European language (e.g., French, German, or Spanish) is advantageous but not required. 

Internship details 

  • Location: London 
  • Duration: 4 to 8 months, full-time 
  • Start window: Between Early May and Early July 2026 

If you’re excited by real responsibility, steep learning curves, and the chance to help shape Europe’s energy future, we’d love to hear from you.