Independent Advisory Practice · Established 2011
Quiet authority for the world's most consequential boardrooms.
Strategic counsel for CEOs, founders, and institutional leaders navigating irreversible decisions.
Currently accepting principals for Q2 2026 — waitlist reviewed quarterly.
On the Practice
A confidential sounding board for decisions that cannot be made in the principal's own room.
Sigrid Verbert advises fewer than forty principals at any time. The figures, the chairmen, the founders approaching a sale, an IPO, a contested succession, or the slow aftermath of a crisis that has not yet resolved — they retain her not for answers they can find elsewhere, but for the questions no one else in the room is willing to ask. Sessions are private, unscripted, and conducted in English, French, German, or Dutch without translation.
After eighteen years inside a FTSE 100 insurer — the last five as General Counsel — and nine years as a senior partner at McKinsey & Company, Sigrid founded her independent practice in 2011 with a single rule: a hard cap on concurrent clients, enforced by personal policy rather than by capacity. She now sits on six boards, has briefed fourteen sitting cabinet ministers and three central bank governors in confidential roundtables, and writes regularly for the Financial Times, Handelsblatt, and Les Échos. Her 2019 Harvard Business Review piece, "The Quiet CEO Problem," remains the most-cited practitioner article on board dynamics from that year.
The work is not coaching in any conventional sense, and it is not legal representation. It is the discipline of being the one person in the principal's professional life who has read the file, knows the politics, and will say plainly what the board, the chair, or the founder cannot say to themselves before the decision becomes irreversible.
Evidence
Five facts the principal is entitled to before the first conversation.
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38
Concurrent principals — a deliberate scarcity cap, in force since 2014.
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5.7yr
Average client tenure; twenty-two principals now in their seventh year or beyond.
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81%
Of diagnostics convert to a six-to-eighteen-month retainer.
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100%
Principal-renewal rate across the last four retainer cohorts.
How an Engagement Begins
Three deliberate steps, not a funnel.
Seventy-one per cent of new principals arrive by referral from existing clients. The remainder are welcomed through the same gate.
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I
A confidential written enquiry.
The principal, or a chief of staff acting on their behalf, sends a short letter outlining the situation. Replies are issued within five working days, signed by Sigrid personally. No discovery call is scheduled until there is a clear basis for one.
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II
A ninety-minute diagnostic conversation.
A paid engagement at €4,500, conducted in Brussels, London, or by secure video. The conversation surfaces the live questions, tests fit, and produces a written read-out within seven days. No retainer is implied.
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III
A decision the principal controls.
Following the diagnostic, the principal decides whether to enter a retainer — typically six to eighteen months, reviewed quarterly. Eighty-one per cent of diagnostics convert; nineteen per cent do not, by design.
“I am not retained for what I know. I am retained for the question no one in the room is still willing to ask.”
— the working premise of the practice
Begin
Request a Diagnostic Conversation.
A ninety-minute, paid engagement at €4,500. Reviewed quarterly. Discreet from first contact.
Request a Diagnostic ConversationOr write directly · [email protected] · +32 2 555 0142
Sigrid Verbert Advisory SRL · Avenue Louise 480, 1050 Brussels · Registered in Belgium · London office by appointment.