Sunstone Advisory is an independent transaction advisory firm working with companies, founders, family businesses and investors in situations where ownership, leadership and capital intersect. Our mandate covers M&A advisory, portfolio and exit work, and fundraising advisory — high-stakes processes where the quality of the advice matters as much as the quality of the execution.
We bring the perspective of an investor: not just understanding how processes work, but how the other side of the table actually thinks, negotiates and decides.
Complex transactions — whether a sale process, a fundraising round or an ownership transition — require an advisor who has genuinely sat on both sides of the table. Most advisors have spent their careers in investment banking or in private equity, not both. The distinction matters.
A banker understands process mechanics, documentation and execution timelines. An investor understands how opportunities are assessed, how assumptions are stress-tested, and how value creation narratives are evaluated by those writing the cheques. Bringing these two perspectives into a single mandate reduces the friction that derails otherwise sound transactions.
Sunstone Advisory was founded on the conviction that independent advisory — without the conflicts of a large institution — is the most effective form of transactional support.
We manage the full transactional cycle — from process preparation through closing. This includes process management, due diligence oversight, valuation and structuring, financing advisory, negotiation and documentation. Whether on the buy side or the sell side, our involvement is direct and continuous: we act as a counterpart to management throughout, not a peripheral voice.
Between acquisition and exit, value is created — or lost — through a series of operational, financial and strategic decisions. We work alongside portfolio companies and their investors on value creation execution, add-on acquisitions, board and investor interactions, refinancing, and equity story development. When the time comes to exit, we prepare the process, refine the narrative and manage the execution.
A fundraising process is as demanding as any M&A transaction — and the quality of preparation is what separates a clean close from a protracted one. We drive the full process: equity story construction, investor materials, Q&A preparation, investor follow-up and tracking, term sheet negotiation and documentation. We manage the process so that management can stay focused on running the business.
Marine Charbonnier, founder of Sunstone Advisory, brings a decade of investment banking and private equity experience to every mandate.
Marine began her career at Deutsche Bank in Investment Banking, where she structured and executed transactions across M&A and financing. She subsequently joined The Carlyle Group's European Buyout fund as an Associate, where she assessed, negotiated, owned and sold companies as a principal investor. The combination of these two disciplines — deal execution and investor judgment — is the foundation of Sunstone Advisory.
Marine holds a degree from Université Paris Dauphine.
Over the course of her career, Marine has assessed more than a hundred opportunities across sectors and transaction types — large-cap flagship investments, mid-market acquisitions, disposals, add-ons, financings and fundraisings. More than twenty have been closed.
An investor's perspective built into the process.
We challenge analysis, pressure-test assumptions and sharpen investment cases — not as an afterthought, but as a core part of how we run a mandate. Having evaluated and owned companies as a principal investor means we understand not just what buyers and investors want to see, but how they actually decide.
Hands-on, not hands-off.
We are not a firm that produces deliverables and steps back. We structure, negotiate and decide alongside you. Every mandate is handled directly — no junior layers, no dilution of seniority. The partner you engage is the partner who does the work.
Fully independent. Fully aligned.
As an independent advisory firm, we have no proprietary products to push, no financing mandates to protect, no cross-selling agenda. Our interests are aligned entirely with yours. The advice we give reflects what we believe is right for your transaction — nothing else.