Analyst Craig Moffett noted a series of articles by The Wall Street Journal (WSJ) into the existence of potentially toxic lead-sheathed cables in AT&T and Verizon’s networks could result in a continued sell-off of telecom stocks.

AT&T, Verizon, Lumen Technologies and Frontier Communications have all seen their stock values plummet since the first WSJ article was published on 9 July.

Moffett estimated the operators shed a combined $18 billion in market capitalisation for a weighted average decline of 6.4 per cent, but conceded he is unable to accurately measure the potential risk.

“How big a deal is this? The unsatisfying, but honest, answer is that at this point we have nothing but unknowns to work with and no real way to quantify the companies’ exposures.”

WSJ reported around 2,000 lead-sheathed cables remain deployed underwater, in soil and on poles, but the actual number could be higher.

Moffett stated once operators started phasing out lead cables in the 1950s and 1960s, no one has a real understanding of how many are still around or in use.

“We’d be shocked if the carriers had accurate, comprehensive [data] regarding the presence or location of all of the lead cables in their networks.”

Moffett stated Verizon and AT&T will likely have the greatest potential for exposure in monetary terms given the size of their respective fixed footprints, but noted this is a smaller part of their businesses than for Lumen Technologies and Frontier Communications.

WSJ reported environmental groups asked the US Environmental Protection Agency to remove the cables immediately due to potential health risks for children.