Myth: a bottom anchor unit is free money

Myth: a bottom anchor unit is free money

Anchors get sold as the no-downside RPM hack. They have a real one.

What it does — pins a sticky banner to the screen edge for huge viewability.
Setup effort — 1/5.
The correction — anchors don't add net demand; they pull spend from your in-content units, so total RPM rises less than the anchor's own RPM suggests. And mobile anchors that overlap your CTA or navigation quietly raise pogo-sticking, which dings session quality and long-term ranking.
RPM lift seen — net +3-5% page RPM, not the +15% the anchor's own line item implies.
Pros — bulletproof viewability, easy fill.
Cons — cannibalization, UX/policy risk on tap-targets.

Lift: ★★★☆☆ — Risk: ★★★☆☆
Best for: content with no bottom CTA. Skip on conversion-driven pages where the anchor covers buttons.