The penthouse of the sleek, postmodern Metropolitan Tower in Midtown Manhattan offers panoramic views of New York. But for more than five years, a former Wall Street trader used it as a sex "dungeon," luring women in and leaving them maimed and bruised, federal prosecutors say. Howard Rubin, 70, a former Salomon Brothers bond trader ... was arrested Friday on sex trafficking charges. Prosecutors said he brought women to the penthouse blocks from Central Park, where a bedroom was painted red, soundproofed and fitted with devices to use on the women. Along with a personal assistant, Jennifer Powers, Mr. Rubin recruited and paid at least a half-dozen women to participate in bondage and sadomasochism, but the acts went far beyond what the women had signed up for. Prosecutors said Mr. Rubin took advantage of the women, many of whom were especially vulnerable because of their histories of addiction and abuse. Though women were told they could use a "safe word" to stop any sexual encounter, prosecutors said they were often unable to utter it because they were gagged or Mr. Rubin simply ignored their pleas. The room would often remain locked during the encounters ... while the women were shocked, beaten and violated. Mr. Rubin also provided the women with copious amounts of drugs and alcohol before their sex acts. In one encounter, Mr. Rubin gave a female victim a sedative that made her unconscious so he could enact a rape fantasy.