Some leading Wall Street and European banks are avoiding mentions of Hong Kong’s anti-government protests in the research they supply to clients, out of fears they will upset Beijing and risk an increasingly important source of revenue.

Banks in the city have said in private that discussing the market impact of months of simmering political unrest is too sensitive, underscoring the challenges faced by bankers in the restive finance hub.

An executive at one European bank — which wants to boost its business in mainland China — said its analysts had been told not to write about the protests in research distributed to clients such as institutional investors. Another executive at a separate Europe-based bank said: “No one wants to stick their necks out by saying something about the [Hong Kong] situation.”