Banks are on a hiring spree to compete for market share in sustainable debt, one of the fastest-growing parts of finance.

Firms including Citigroup Inc., HSBC Holdings Plc, and Barclays Plc have snapped up people for bond sales, research or global sustainability roles this year as they build teams. Aside from poaching talent, they are tapping expertise among scientists, politicians and think tanks.

“We are actively hiring, we typically get 100 plus CVs per role,” said Arthur Krebbers, head of sustainability, corporates at NatWest Markets Plc, whose expansion has pushed it into the top 10 sustainable debt underwriters this year.

The rush for staff shows the rise of debt tied to environmental, social or governance factors as an emerging money-spinning asset class for banks. They have already made an estimated $1.8 billion in fees so far this year from such customers, and that will likely climb in a market seen growing five-fold by Bloomberg Intelligence to $11 trillion in 2025.

This is also part of a broader effort by banks to navigate a push by global policy makers toward a lower carbon future. They have been earning even more in fees from raising money from fossil-fuel clients, yet are under pressure from activists and shareholders to exit such business.