With more tumult in local television news ratings than there has been in a decade, ad buyers said this November sweeps period has the potential to significantly affect stations’ ad rates—and financial fortunes—for 2011.

If the November viewer numbers tabulated by New York-based Nielsen Media Research are close to the sweeps periods in July and October, the market’s leader, WTHR-TV Channel 13, could see demand for advertising during its newscasts decrease. For a station that has been the perennial local TV news ratings leader, the shift in power could be quite a jolt.

Television viewer ratings for the November sweeps period, ad buyers said, sets the stations’ advertising rates for the first half of the following year.

Gains by WISH-TV Channel 8 and WXIN-TV Channel 59 have media buyers eyeing this year’s November sweeps especially closely, with some wondering if WTHR will change its strategy in local news programming.

“Over the last year or so, WTHR’s ratings have slipped, and the other stations have started to catch up,” said Sue Doron, media director for EchoPoint Media, the media buying arm of ad agency Young & Laramore. “What we’re seeing is the other stations working hard to improve their local news, and as a result, there’s more parity in the market. As a buyer, I like having more options for my clients, but I’m sure this is a concern for WTHR.”

Bill Perkins, a longtime local media buyer and president of Perkins Nichols Media, noted that the overall central Indiana TV viewing audience is not growing.

“So when one station grows viewership, that growth is coming from somewhere else,” Perkins said. He said a recent change in WTHR’s news director position “indicates they have a problem.”

WTHR General Manager John Cardenas did not return calls seeking comment.

Advertising sold during local newscasts is stations’ largest single source of revenue, usually 40 percent to 60 percent of the total.

In recent years, WTHR has been able to charge 25 percent more for ads than WISH and more than 50 percent more than WXIN and WRTV-TV Channel 6. A 30-second spot during the local news can run anywhere from $600 to $1,500.

Ratings declines over two or three sweeps period might be enough to soften the demand for any TV show, Perkins said.

WTHR, an NBC affiliate, has been hit especially hard during the morning hours. Comparing weekday newscasts from October 2010 to October 2009, WTHR saw its local news rating decline 39.1 percent during the 5 a.m. slot, 31.3 percent at 5:30 a.m., and 28.7 percent at 6 a.m.

Meanwhile, WTHR’s main competitor, WISH, a CBS affiliate, saw ratings increases of 38.1 percent, 50.2 percent and 19.8 percent during the same time slots in the October year-over-year comparison.

“It continues to be a battle with WTHR and the other stations, but I really like the direction we’re headed,” said WISH General Manager Jeff White. “We’re aggressively getting out there to deliver hard news, and people are taking notice.”

WXIN, a Fox affiliate, is also gaining ground with its morning news, and WRTV, an ABC affiliate, is holding its own, though it still lags the others.

Even more troubling for WTHR, Perkins said, is that NBC’s “Today Show” gets nearly double the ratings of national morning news programs on ABC and CBS.

Despite the declines, WTHR is still the ratings leader during several local news time slots throughout the day. But gone are the days when WTHR’s ratings equaled that of its competitors combined.

WTHR was up slightly during the noon news in October compared with the same period a year ago, but during the 5 p.m., 5:30 p.m. and 6 p.m. slots, it is down 7.6 percent to 12.9 percent. WISH and WRTV, too, are down during those times—even more than WTHR, while WXIN’s 4 p.m. news is up 22.3 percent and its 5 p.m. news is up slightly from the syndicated programming that appeared in that slot a year ago.

Despite poor ratings for NBC’s prime-time lineup, WTHR remains in a close battle with WISH for the 11 p.m. news rating lead.•