Halo Effect (Paid-to-Organic Spillover)

A 2026 empirical study of ad shutoffs found that turning off Apple Search Ads spend for a keyword reduced organic installs for that keyword by 20 to 30 percent, and that panel data across longer periods associated every $100 in ad spend with roughly 32 paid installs and 2.2 additional organic installs. That is a real, measured spillover, not marketing folklore.

The mechanism, as best understood, runs through ranking rather than direct causation: paid installs raise download velocity for a keyword, download velocity is one of the multipliers in Apple's ranking formula, and the resulting rank increase pulls in organic traffic that would not otherwise have found the app. A high tap-through rate on a paid placement is also read as a relevance signal for that query.

Apple has never officially confirmed a direct organic ranking boost from running ads, and the effect is not the same as fraudulently inflating rank — it's an indirect consequence of the same velocity and engagement signals that reward any legitimate install spike. This is one reason a burst of paid installs on a moderate-difficulty keyword can produce ranking lift that outlasts the campaign, while the same spend on a highly entrenched keyword often does not.