Taking one of the hardest lines to head off financial conflicts of interest in the media industry, CNBC said that its managers and news staff and their spouses and dependents would no longer be allowed to own individual securities, other than those of their employers. The rest of the network's full-time employees, all the way down to those who apply makeup and hairspray to guests, will be able to keep any securities they own, but will not be allowed to buy more.