doubt (6)

He said despite being ultimately owned by pension fund members, who have a long-term investment horizon, companies feel under constant and immediate pressure to perform. 'It's completely mad,' he says. 'Business people need to think: Hang on a minute, when I think about creating value for owners, I need to remember that the shareholders are millions of people. And pensioners need to think: What is my role as a capitalist?'

1/ In companies feel under constant and immediate pressure to perform, constant is an adjectif and pressure is a noun. Why? It isn't parallel structure?Could you explain why the author use this strange structure?

2/Please interpret companies feel under constant and immediate pressure to perform.

Quoc