CNBC is dropping out of the daytime Nielsen ratings game, according to a report in Adweek, which says the financial news network will turn to its internal numbers as the basis for ad sales.

The report quotes a source saying: "They are no longer guaranteeing the business day, which is the most important daypart for a financial client. They believe that their primary business day viewing is done in offices and therefore not monitored by Nielsen and underrepresented."

The move comes after CNBC’s ratings have grown smaller in the past few years, and with smaller audiences, Nielsen’s ratings become less accurate, the story notes. The network will continue to guarantee its prime-time shows, the report adds.

“But, of course, CNBC is also one of the few networks for which daytime ratings aren't a particularly accurate measure of relevant reach,” Adweek notes.

The report adds: “Monitors throughout the Goldman Sachs building play the network to their wealthy executives. The network's show ‘Squawk on the Street' broadcasts from inside the New York Stock Exchange. If you work in the financial world — a small world, but one with nearly unlimited spending money — CNBC is ubiquitous in gyms, hotels and elsewhere among areas frequented by bankers and traders.”

Because of that small but focused audience, CNBC’s executives have often argued that it doesn’t matter as much when certain demographic groups decide to watch “Breaking Bad,” the story says.

“Instead, said a source close to the network, the company is offering guarantees based on its own internal measurement of ad deliveries,” the article notes. “It's not an ideal situation, certainly — third-party measurement is a large part of what makes TV advertising so valuable — but parent company NBCUniversal has been revising its advertising sales apparatus radically in recent months.”

Seth Winter, executive vice president of the news and sports ad sales group for the network, told Adweek, “While we completely agree that CNBC's core audience remains virtually unmeasured by current traditional metrics, our agreements with our clients are confidential.”