ermmm confusing question . .. pliz help

[kutu_suci]

a central challenge for anyone running the firm is raising the funds needed to operate and expand the business.

my questn is Why it doesn't use "that are" in front of "needed" ? so it will be like "a central challenge for anyone running the firm is raising the funds that are needed to operate and expand the business."

could u explain it why and give the examples that are using this grammar rule. thanks

 

[Tdol]

It's a reduced relative clause. We can replace the verb with a present or past participle and remove the pronoun:

The man who lives across the road => the man living across the road
The funds that are need => The funds needed