In another ominous sign for the US pay-TV industry, a new study revealed that that the industry's penetration rate is slipping even as the number of potential customers keeps going up.

The study, conducted by Leichtman Research Group Inc. (LRG) , found that 84% of US households now subscribe to some type of multi-channel video service from cable, telco or satellite TV operators. While that number is still very high, it represents a notable drop from the peak 87% penetration rate seen in both 2010 and 2012, following the broadcast TV transition to digital transmission. As such, it reinforces other data indicating that the giant US pay-TV market is now shrinking for the first time in the industry's 65-year history. (See US Pay-TV Subs Renew Plunge and Cord-Cutting Slows But Danger Still Real – Moffett .)

In its 12th annual telephone survey on this topic, LRG found that the actual number of pay-TV households "has been fairly flat over the past four years," leveling off at around 100 million homes. But, with steady population growth and an increase in the number of US households, the penetration rate has dropped.

In a separate report last week, The Nielsen Co. estimated that there are now 116.4 million TV households in the US, up 0.5% from a year earlier. Nielsen also estimated that about 96% of these homes actually receive some type of TV service, including free over-the-air broadcast television.

Bruce Leichtman, president and principal analyst for LRG, blamed the unprecedented decline in the pay-TV penetration rate on the changing makeup of new US households. He noted that most, if not all, of the household growth has been "among renters, who tend to be more challenging for the pay-TV industry than home owners because of their comparatively lower income, younger age and greater likelihood to move."

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Buttressing this point, the latest study found that 22% of households with annual incomes below $50,000 don't subscribe to a pay-TV service, while just 13% of those with incomes over $50,000 don't subscribe. Moreover, 22% of those who moved in the past year don't subscribe, up from previous years.

At the same time, the cost of pay-TV service continues to climb. The study found that the mean household spend on multi-channel video is now $89.78 per month, up 36% over the last five years in a period of low general inflation.

In one of those glass half-empty or half-full findings, only 11% of non-subscribers cited Netflix Inc. (Nasdaq: NFLX) or the Internet as their main reason for not taking a pay-TV service. However, that percentage has nearly quadrupled from a mere 3% in 2009.

Finally, in another sign to watch for the industry, about 12% of both cable TV and telco TV customers said they are likely to switch providers in the next six months. Slightly fewer satellite TV customers, or 11%, said they are likely to switch as well.

— Alan Breznick, Cable/Video Practice Leader, Light Reading