What is the importance of CHOAM in the novel, Dune?

An acronym for the "Combine Honnete Ober Advancer Mercantiles," CHOAM is economic pillars of galactic civilization, having a monopoly on the sale of the geriatric spice melange. The Emperor Shaddam IV and his allies control 59.65% of CHOAM directorship votes, smell vast profits, and are intent on controlling more. At the end of the novel, the victorious Duke Paul-Muad'Dib Atreides demands all of Shaddam's shares as part of the forced dowry given for his eldest daughter, Irulan. Paul's lieutenant, Gurney Halleck, is to receive a directorship as well.