FASTMaster's audit of the Martha Stewart Channel across five major FAST services exposes how channel-count dominance no longer guarantees ad revenue—even as Wurl data shows total FAST viewing surging 29% year over year.

Samsung TV Plus homepage. Smosh, Challenge Accepted, Mark Rober TV and The Martha Stewart Channel sit front-and-center—the lifestyle and creator-led channels that anchor today's FAST shelf. (Source: Samsung TV Plus)

Same 30-minute episode. Same ad slot. Roughly threefold revenue gap.

That is the picture emerging from US media analyst FASTMaster's simultaneous audit of the Martha Stewart Channel across five major FAST (Free Ad-Supported Streaming TV) services. The Roku Channel and Pluto TV sold every ad slot for a perfect 100% fill rate, while Amazon's Prime Video—despite carrying more than 800 FAST channels, the largest collection in the market—filled just 33% of its inventory.

같은 채널인데 광고 충전율은 33% vs 100%...FAST 광고 시장, 플랫폼 선택이 새 승부처로FAST플랫폼의 변신. 같은 FAST 채널이라도 플랫폼에 따라 광고 충전율이 33%에서 100%까지 갈려. 채널 수를 무한히 늘리는 전략보다 ‘어느 플랫폼에서 얼마나 잘 팔리느냐’가 FAST 광고 수익의 결정적 변수K-EnterTech HubJung Han

The takeaway is straightforward: in the FAST ad economy, channel volume is no longer a reliable proxy for revenue. The market is moving from a land-grab phase into an efficiency phase, and platform selection has emerged as a top-line variable for content suppliers, including the Korean drama and reality producers eyeing global FAST distribution.

The macro backdrop is robustly bullish. Wurl, the AppLovin-owned SaaS provider for FAST companies, released its 2025 "CTV Trends Report" on Sept. 30 showing FAST monthly active households up 12% year over year, daily viewing per household up 16%, and total FAST hours of viewing up roughly 29%. The catch—and the reason the FASTMaster numbers matter—is that advertiser demand has not kept pace with the explosive expansion of channel inventory. Platforms that grew most aggressively are now sitting on the most unsold "we'll be back" slates.

"Having the largest collection of FAST channels does not guarantee increased profitability. This inflated supply simply outpaces market demand, showing infinite inventory virtually guarantees unsold slates."

— FASTMaster Intelligence Analysis

◆ FASTMaster's Experiment: One Episode, Five Screens

On March 19, FASTMaster ran a deceptively simple field test. Five screens were tuned simultaneously to the Martha Stewart Channel—via Pluto TV, Roku Channel, Prime Video, Samsung TV Plus and Xumo Play—and team members logged ad time and unfilled-slate time to the second across the same 30-minute episode. The methodology isolated the platform variable: identical content, identical timeslot, varying ad operations.

Ad fill rates for the same Martha Stewart Channel episode across five FAST platforms. Pink = filled ad time; purple = unfilled slate. Prime Video left 67% of its commercial breaks unsold. (Source: FASTMaster Intelligence Analysis, March 19, 2026)

The numbers split sharply. Total ad load varied platform-to-platform: Roku ran four minutes of commercials, Pluto TV ran seven, while Samsung TV Plus and Xumo Play each carried six. But the bigger story was sell-through. Roku and Pluto cleared 100%. Samsung TV Plus and Xumo trailed at 90% and 85%. Prime Video filled just two of its six minutes—a 33% fill rate, with four minutes of placeholder slate filling the gap.

Platform

Fill Rate

Unsold Slate

Total Ad Time (per 30 min)

Roku Channel

100%

0%

4 minutes

Pluto TV

100%

0%

7 minutes

Samsung TV Plus

90%

10%

6 minutes

Xumo Play

85%

15%

6 minutes

Prime Video

33%

67%

6 minutes (4 unfilled)

Platform-by-platform fill-rate summary, based on FASTMaster measurement

FASTMaster's conclusion was blunt: "Having the largest collection of FAST

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고삼석 상임의장 · Chairman Samseog Ko

고삼석(Ko Samseog)은 K-EnterTech Forum 상임의장입니다. 동국대학교 첨단융합대학 석좌교수이자 국가인공지능전략위원회 분과위원으로, 30년 이상의 방송통신 정책 및 산업 경험을 바탕으로 K-콘텐츠와 글로벌 엔터테인먼트 기술의 융합을 선도하고 있습니다. 前 방송통신위원회 상임위원을 역임했으며, ZDNet Korea에 정기 칼럼을 연재 중입니다.
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