NBC will stop airing national commercials during its overnight rebroadcasts of "Nightly News" after advertisers complained that the network was quietly using the rebroadcasts to bump its ratings, the On Media blog has confirmed. The move means that overnight viewers will no longer be included in "Nightly's" Nielsen ratings.

Since early February, NBC has been quietly rebroadcasting "Nightly" in at least 10 major media markets between 2 and 4 a.m. These airings, which are included in Nielsen's total ratings report, have given NBC an undeclared advantage in the contentious nightly news ratings race. Last week, a major media buying firm contacted NBC requesting that it discontinue its advertising during the rebroadcast, despite the fact that networks are required to run rebroadcasts without changes to the programming or the advertising. 

On Monday, Linda Yaccarino, the chairman for NBC's advertising sales, met with NBCUniversal chief Steve Burke to discuss the situation with advertisers, according to a source with knowledge of the meeting. Starting tonight, the "Nightly" rebroadcasts will run without any national advertising in them. Instead, they will feature local ads and promotions. As such, they will not be included in Nielsen's ratings totals. (Neither ABC nor CBS rebroadcast their nightly news programs.)

NBC News declined to issue a new comment on the matter. In a previous statement, the network claimed that the addition of rebroadcasts was simply meant "to reach our audience when and how they want to be reached." The rebroadcasts gave "Nightly" a relatively small bump -- probably as little as 1 percent -- but that can be a crucial advantage in a contest where the difference between first and second often comes down to just tens of thousands of viewers.

In a press release last week, ABC News took a shot at its competitor in a news release: "NOTE," the second paragraph of the press release read, "NBC’s stated averages now include both its 6:30 p.m. E.T. airings and re-broadcasts on some stations between the hours of 2-4 a.m. E.T. NBC News has not publicly stated the markets in which the re-airs occur nor how many additional viewers they are claiming as a result."

While NBC's decision to air rebroadcasts was the result of months-long negotiations, the change went into effect the same week that Brian Williams came under scrutiny for false claims he had made about his experiences in Iraq. Williams was suspended for six months without pay, and the industry has followed the ratings race closely to see whether or not his replacement, Lester Holt, can sustain NBC's lead.