Harmonic Q3 sales jump 64% as customer base widens beyond Comcast and Spectrum

Harmonic grew third-quarter 2026 revenues 64% year over year to $148.8 million, blowing past both analyst expectations of $129.5 million and its own guidance range of $125 million to $135 million. Behind the number sits a structural shift: for the first time in recent memory, four customers each accounted for 10% or more of quarterly revenues, expanding a concentration long dominated by Comcast and Charter's Spectrum brand.

Harmonic said 37% and 16% of Q3 sales came from Comcast or Spectrum, without matching the figures to specific operators. Raymond James analyst Simon Leopold said in a research note he believes Comcast represented the 37% share and Spectrum the 16%. The company declined to name the other two 10%-plus customers.

How broad is the diversification?

The widening shows up clearly in what Harmonic calls its "rest-of-market" (ROM) revenues — sales to operators other than Comcast and Charter. ROM hit 46% of sales in Q2, double the year-ago level, and represented more than 60% of bookings in that period.

Leopold said the trend points to the success Harmonic is having diversifying its business on a longer-term basis, and to momentum in fiber-to-the-premises (FTTP). "The accelerating growth from the more fragmented group of smaller regional cable operators improves customer diversification, and should improve investor confidence in Harmonic's long-term story," he said.

Harmonic's cOS access network virtualization platform was originally developed for hybrid fiber/coax networks and has since been adapted for FTTP. The company added six cOS customers in Q3, bringing the total to 167, with deployments serving nearly 53 million broadband customer premises devices. Recent wins include Lightcurve and Cablenet, a Cyprus-based operator.

What role does the Int6 Tech acquisition play?

Harmonic is also buying its way deeper into the PON market. It recently closed what it billed as a "tuck-in" acquisition of Int6 Tech, a Brazil-based company whose fiber management platform works with multiple PON vendors. Harmonic's cOS Loop product is built on that platform, handling optical line terminal and optical network terminal provisioning, remote diagnostics, and in-home CPE management.

At Harmonic's investor day in September, President and CEO Nimrod Ben-Natan said Int6 Tech had about 40 customers that together serve roughly 7 million subscribers. On Monday's earnings call, Ben-Natan said cOS Loop continues to perform well with established customers in Brazil and is drawing interest from Harmonic accounts in North America and Europe.

In PON operations, Harmonic has also introduced Recon, a fiber monitoring platform developed with Comcast that proactively pinpoints degradation and fiber cuts. Comcast began deploying fiber-sensing technology last month as part of a reliability push, though it did not name Recon specifically.

Where does the growth go from here?

The fiber activity feeds Harmonic's primary growth engine of connectivity, alongside two longer-term drivers — intelligence and edge AI compute — that it identified at investor day. The company sharpened its broadband focus after selling its video division to MediaKind.

Harmonic ended Q3 with $142.8 million in cash and reiterated that it will continue to explore strategic M&A to further diversify the business.

Fueled by sales momentum outside of Comcast and Spectrum, the company raised full-year 2026 guidance for the third time this year. It now expects revenues of $545 million to $555 million, up from the prior range of $505 million to $525 million. Investors rewarded the print: Harmonic shares were up 2% in midday trading Tuesday.