Italian to English Bus/Financial Real Estate

From a letter of intent between a real estate investment mutual fund and a company providing services to the properties constituting the fund's assets.

Payment for the sales and marketing services the company agrees to provide are made as a percentage of the sales, "incluse eventuali intermediazioni passive."

I did find this doc on the web that gives some context:

http://74.125.155.132/search?q=cache:58MZ3hUszJwJ:my.liuc.it...

It refers to investment companies engaging in real estate negotiations, and says they have a twofold purpose, the first of which is:

"l'assistenza allo scambio diretto fra datori e prenditori di fondi, favorendo l'incontro fra domanda ed offerta e riducendone così i costi di transazione (intermediazione passiva)."

Any ideas of how best to render this in English? Some sort of brokering services? How best to render the "passiva?" Thanks!