Piracy in the US could cost pay-TV operators as much as $4 billion this year, according to Sandvine’s TV piracy report.

The report found that about 6.5% of US households are accessing pirated TV services each month. Premium television, live sports, news, and international content are the main drivers of pirate television usage, but some events stand out: The Mayweather vs. MacGregor boxing match in August accounted for 80% of all pirate streams the evening it occurred, and the event may have been watched by 1% of all households in North America.

There are other costs besides lost pay-per-view and on-demand revenue. The report, based on data collected from multiple fixed access networks in North America, found that many pirate television configurations stream 24/7, whether users are watching or not, resulting in many users generating over 1TB of “phantom bandwidth” across their network each month.

“Continued adoption of pirate video and television streaming services could lead to increased cord-cutting and create ‘cord-nevers,' people who never sign-up for a standard TV subscription, said Lyn Cantor, CEO, Sandvine. “This will significantly impact [service providers’] revenue and profitability, undermining the business models that keep them operating.”