Viacom's ( VIAB) future is up in the air, but its stock continues to lose altitude.With new top managers, a major split-off in the works, and a fluid situation at its radio business, the New York media giant is in the midst of some major transitions. And while the company will no doubt update the Street on these issues when it reports second-quarter earnings Thursday morning, it seems unlikely that Wall Street's open questions will be answered with any degree of finality. Meanwhile, battered by uncertainty -- or, perhaps, a creeping sense of more permanent change for the worse -- Viacom's stock continues its drift downward for the year, hitting lows last seen a year ago March and performing noticeably worse than big-media brethren Time Warner ( TWX) and Disney ( DIS). Viacom is a good company that has done "intelligent" long-term things recently, says Morris Mark, president of Mark Asset Management. But questions about the company's future remain open, says Mark, who doesn't hold any Viacom shares. "We really want to wait and see what happens after they do the Blockbuster ( BBI) exchange offer," he says. "Do they buy stock, or do they buy something else?" Viacom's stock rose 9 cents Tuesday to $33.76, leaving it down 24% from the New Year's Eve close of $44.24.