An interesting attribute of public banks is that they don't only de-risk the downside, but also get a share of the upside.

Brexit and Trump have brought the problems of capitalism into sharp relief, but both are only making things worse. Take the investment challenge - businesses invest where there they see technological or market opportunity.

In my view, the state should be active and work in cooperation with private businesses to spur growth that's sustainable and inclusive. The policy process is about co-creating and co-shaping of markets, creating new opportunities for business investment - and negotiating a better deal for the public too.

Rethinking capitalism means rethinking the role of the public sector, the role of the private sector, the role of finance, and the relationship between them all.

Once we admit that the public sector takes an immense amount of risk along the entire innovation chain, it becomes crucial to find ways to share both risks and rewards.

If we look at Germany's infrastructure policy, it has been driven by its mission-oriented focus on green infrastructure. This affects both innovation and infrastructure, old industries and new. The German steel industry, for example, has adapted to the policy by lowering its material content through a 'repurpose, reuse and recycle' strategy.

We should be investing where the public returns are greatest - that is in innovation.