Harmonic Raises Outlook as Four Customers Top 10%

Harmonic reported third-quarter 2026 sales growth of 64% and raised its full-year revenue guidance.

Updated on Nov. 3, 2026 in Corporate Finance

Isometric editorial illustration of coiled amber fiber-optic cable on a steel reel beside plain gray equipment cabinets on a concrete floor, rendered in muted slate, oxblood, and mustard. — Harmonic raised its full-year 2026 revenue guidance to $545 million to $555 million after third-quarter sales jumped 64%, with Comcast and Spectrum accounting for 37% and 16% of sales. AI Illustration. Upload story photo >

Harmonic said four customers each accounted for 10% or more of third-quarter 2026 revenues, with Comcast and Spectrum representing 37% and 16% of sales, respectively. The company raised its full-year 2026 revenue guidance to $545 million to $555 million.

Why it matters

The disclosure shows Harmonic diversifying beyond a narrow customer base as its rest-of-market revenues doubled from a year earlier. Analysts expect the shift to strengthen investor confidence in the company's long-term growth story.

Harmonic ended Q3 2026 with $142.8 million in cash and 167 total cOS customers after adding six in the quarter. The company did not identify the operators behind two of the four 10%-plus customers, leaving their revenue share unexplained.

The players

Harmonic Inc.

Harmonic is a video and broadband technology company whose cOS platform serves cable and fiber network operators worldwide.

Comcast

Comcast is one of the largest cable and broadband providers in the United States and a major Harmonic customer.

Spectrum

Spectrum is the cable and broadband brand of Charter Communications and a significant Harmonic customer.

Simon Leopold

Simon Leopold is an analyst at Raymond James who covers communications equipment companies and commented on Harmonic's diversification.

The details

Harmonic acquired Int6 Tech, a Brazil-based company whose fiber management platform works with multiple PON vendors, and its cOS Loop product is built on that platform. The company also introduced Recon, a fiber monitoring platform developed with Comcast, and cOS deployments now serve 53 million broadband customers-premises equipment units.

September 2026: Harmonic presented Int6 Tech customer figures at an investor day.
Q2 2026: Rest-of-market revenues reached 46% of company sales.
Q3 2026: Four customers topped 10% of revenues as sales rose 64%.
Tuesday, November 3, 2026: Harmonic shares rose 2% in midday trading.

Market Landscape

Harmonic's rest-of-market revenues doubling from a year earlier marks a shift away from reliance on a few large cable operators. The move positions the company to compete more broadly across the fiber and broadband equipment sector.

Investors tracking Harmonic can now see that four customers each drove at least 10% of quarterly revenue, a level of concentration that carries risk if any major operator reduces spending. The raised guidance of $545 million to $555 million gives a clearer near-term revenue target for the year.

The takeaway

Harmonic's revenue mix is broadening as cOS adoption grows, which reduces dependence on a few large operators. Readers following the stock should watch whether rest-of-market revenue keeps climbing in coming quarters.