Uncertainty requires adaptability

Having grown up moving from one city to the next, he later worked in China, where he realised his tried‑and‑tested approach no longer worked. Since then, he has led a major transformation at one of the Netherlands’ largest real estate investors.

The only certainty is uncertainty

Siezen has a clear view on this: the concept of crisis has become hollow. In the past, there was a crisis, you solved it, and stability returned. That model no longer holds. Uncertainty is not something that passes — it is the permanent condition. Anyone who waits for calm before acting waits too long.

His answer: long-term certainty, based on macro trends such as demographics and geopolitics, combined with uncertainty about the path towards it. That path is anything but predetermined. The direction, however, is. That distinction — horizon versus route — makes the difference between paralysis and movement.

At Bouwinvest, this means steering on what the real estate market is likely to look like in ten years’ time, based on population growth and the energy transition, while continuously adjusting the day-to-day course. This requires an organisation that does not steer on certainty, but on adaptability. And a leader who understands the difference between what he can influence and what he must let go.

Inward first, then outward

When something unexpected happens, Siezen’s first move is inward, not outward. He has learned that by first looking at himself, he gains more control over his own response. The solution begins with the question: what does this do to me, and why?

He says this without romanticism. Learning it took him through a painful process: a moment in his career when he truly hit rock bottom and only then realised that his way of looking at things was itself the problem. That insight changed him — as a leader, as a father, as a friend. He is grateful for it, even though he would rather have avoided it at the time.

What he adds is a nuance he likes to pass on to others: doubt is not a weakness. He would find it more unsettling if it were absent. It gives him perspective, keeps certainty in check, and makes him a better conversation partner for the people around him. But it comes at a cost: sometimes it affects decisiveness, sometimes time, sometimes credibility. That is a conscious trade-off.

Transformation pace and the elastic of the organisation

The transformation at Bouwinvest is now behind them. One of the dilemmas he struggled with most during that transformation was speed. How fast can you take an organisation along without losing it? His answer is not a formula but a heuristic: if roughly half of your people think it is going too fast and the other half think it is going too slow, then you are truly in motion.

It sounds casual, but it masks a serious leadership challenge. Siezen acknowledges that he has a tendency to want to please: to take everyone along, to leave no one behind. He has learned that this tendency can paralyse him.

His conclusion is uncomfortable but clear: what was good does not have to be right for what is coming. The team that brought the organisation to where it is now is not necessarily the team that will take it to the next phase. Saying that comes at a cost. Not saying it costs more.

Risk-aware, but optimistic

Siezen sees himself as risk-aware. At the same time, there is a difference between being risk-aware and being pessimistic. He believes those two are too often confused. Identifying and naming all risks does not mean he thinks things will go wrong. He wants to understand what is at stake when he acts.

What makes him optimistic is not a naïve belief that things will work out. He finds that too passive. It is a belief in people’s ability to find a way, to shape circumstances. Not waiting, but acting. Not hoping, but building.

This attitude is partly innate, partly shaped by a childhood full of moves. But he is cautious about concluding that circumstances shape people: his brothers went through exactly the same experiences and emerged very differently. Adaptability in uncertainty is partly hard-wired and partly learned. Which part is larger, he does not know. But he is glad to have both.

Showing doubt, while acting decisively

One of his core lessons on leadership in uncertainty is a distinction he likes to pass on to other leaders: do not confuse doubt with weakness. Vulnerability holds enormous strength.

Siezen prefers to share that doubt with people who genuinely tell him what they think, not what they believe he wants to hear. They do not act out of fear or self-interest. For him, that is the definition of trust.

His greatest fear as a leader is isolation. That his position determines how people look at him, rather than who he is. That he stops hearing what is really going on. His response to that risk is deliberate: keeping people around him who do not look up to him, but do value him.

What he wants to pass on to executives

The transformation in China was his most formative leadership moment. He arrived with his tried-and-tested toolkit and discovered that it fell completely short. A different sector, a different country, a completely different corporate culture. Everything he thought he knew about leadership turned out to be context-bound. Only at the lowest point did he realise: this could well all come down to me.

What he took away from that moment is a shift in his view of what a leader is. Not the one who can do everything best, knows the most and runs the fastest. But the one who sees that in others and brings it together. Who creates room to fail. Who supports and also lets go when needed.

His advice to other leaders in uncertain times is compact: know what you can do, know what you can't do, and know that it is entirely normal not to be able to do everything. Find people around you who will tell you the truth. And make sure that outside the role you remain the same person as inside it. Whoever loses the latter will ultimately also lose the former.

Mark Siezen shows that leadership in uncertainty does not begin with having the answers, but with the willingness to be honest about what you don't know: with yourself, and with the people you trust. That is not a sign of weakness. It is the precondition for everything that follows.

Leadership in uncertainty starts with self-insight and the courage to show it.

That is the common thread in this conversation with Siezen and in the conversations Odgers Netherlands holds each year with executives and supervisory boards. Those insights form the basis of this series and of the way we guide organisations through their most important leadership questions.

Curious to see what that looks like in practice? Get in touch!