CBS Corp reported dismal 1st-quarter earnings and posted a $55.3 million loss because 2/3s of the company depends on advertising whose TV, radio and other spending plunged. But Les Moonves told a conference call with Wall Street analysts today that his network’s fortunes will improve in the 2nd half of 2009 and will benefit when it sells commercial time for the upcoming Fall season. He attributed that to developments like NBC’s decision to strip Jay Leno’s show at 10 PM weekdays. He noted that CBS ratings are up strongly among key audiences, and advertising dollars and rates will follow that growth. “In addition, we think we can increase the shift of dollars to CBS, because of NBC’s decision to exit scripted programming at 10 PM. Even if total volume is down at the upfront, we’re confident that we will take share and maintain or increase our revenue.”

CBS Corp’s 1st-quarter loss on plunging advertising revenue at its O&O TV stations, radio stations and outdoor advertising business followed other Big Media trends. But Moonves was quick to stress that the ad marketplace is beginning to get better. Which echoes what Viacom prez Phillippe Dauman and Disney CEO Bob Iger and News Corp Chairman Rupert Murdoch also said at the time of their quarterly reports. As Moonves predicted in a statement: “We are confident that the second half of the year will bring improved results due to a strong slate of syndication releases, the effect of cost reductions that were made last year and early signs of an improving local advertising marketplace.”

CBS shares fell 8% in after-hours trading. According to its 1st-quarter reporting, TV revenue fell 12%, Home Entertaiment revenue rose by 69%, Outdoor Advertising revenue decreased 24%, CBS Radio revenue fell 29%, Simon & Schuster publishing division revenue fell 20%, but CBS Interactive revenue more than doubled — reflecting the company’s acquisition of CNET Networks — but without that revenue would have fallen 5%.