While the 2011-12 upfront will be remembered for the sheer volume of dollars secured by the networks, one media agency titan won’t be looking back fondly on the spring selling season. According to multiple industry sources, GroupM badly misread the cable market, calculating their planning costs two to three points south of the rates negotiated by rival agencies.

As a result, GroupM only has a few deals completed with the major cable network units, and those with outstanding business with the agency are refusing to budge.

To complicate matters, GroupM has insisted that cable networks invest in its year-old media bartering initiative, the Midas Exchange. The practice of swapping excess inventory or other under-performing corporate assets for media credits is nothing new—Omnicom Group’s Icon International has been trading on unwanted and idle property for 25 years.

GroupM vehemently denied that it has strong-armed sellers to back the exchange, noting that the service is merely a single arrow in its quiver. The agency also dismissed network beefs, charging that the sellers were guilty of trying to negotiate rates in the press.

As of June 24, GroupM remained at odds with Turner Broadcasting, Discovery Communications, A&E Networks and FX Networks. Because it handles Paramount Pictures’ $450 million media budget, GroupM had an incentive to hash out an early deal with Viacom’s MTV Networks.

While cable waits for GroupM to come to terms, the final take for the upfront should add up to around $18.5 billion altogether, with broadcast accounting for roughly half of that amount. The Big Five finished up 5 percent from a volume perspective, while cable is expected to improve its dollar haul by as much as 15 percent.

It’s worth noting that upfront commitments don’t necessarily translate into hard and fast revenue figures. Clients have the right to exercise cancellation options if money gets tight, and they can dump as much as 50 percent of their upfront buys in the second and third quarters. (Normally, pullback doesn’t exceed 10 percent in a given quarter.)

On Thursday, UBS analyst John Janedis warned that cancellations could be in the offing. “The scatter market has finally started to slow, which could impact results as early as Q3,” he said. “Higher cancellations could also be a factor.”

As the deadline for Q3 cancellations has come and gone, and because options are off the table in the fall, Janedis’ fears may be groundless. That said, Japanese automakers have pulled back on third-quarter commitments, as the country’s supply chain has been disrupted by the March 11 disaster. Procter and Gamble has also pulled out on some of its TV commitments. Far and away the biggest TV spender, P&G last year invested $895 million in national cable buys and another $710 million in broadcast.