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Overview
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To Do’s
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Question
If teen user engagement were to decline by 5%, 10%, 15% or 20% due algorithmic change, how would the overall engagement in Meta Platforms look like?
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This model estimates the impact on Meta's overall engagement and revenue if teen user engagement declines as a result of court-ordered or regulatory algorithmic changes following the youth addiction trials.
Baseline inputs (FY2025)
| Assumption | Value used | Basis |
|---|---|---|
| Teen share of total time-spent | ~7% | Derived: teens ~4% of users × ~1.8× engagement intensity vs. adults |
| Teen engagement intensity vs. adults | 1.8× | Gen Z spends ~2× time on Instagram vs. Gen X (public data) |
| Algorithm spillover to adults | 20% | Structural estimate: Reels/infinite scroll mechanics built partly around teen behaviour now power adult retention |
| Revenue pass-through from time-spent | 85% | AI targeting efficiency partially offsets inventory volume declines |
| Teen share of users (global) | ~4% | ~22M US teens × ~60% Instagram usage; smaller share globally given Facebook's weak teen penetration |
Important caveat: Meta does not disclose teen time-spent as a share of total. The 7% figure is a derived estimate, not a disclosed number. The spillover assumption has no public empirical basis — it reflects structural logic. Treat outputs as a scenario framework, not a point forecast.
Direct effect + algorithm spillover to adult users
| Teen engagement decline | Direct time-spent loss | Spillover to adults | Total time-spent decline | Severity |
|---|---|---|---|---|
| Baseline (no change) | 0.00% | 0.00% | 0.00% | None |
| 5% | 0.35% | 0.19% | 0.54% | Low |
| 10% | 0.70% | 0.38% | 1.08% | Moderate |
| 15% | 1.05% | 0.57% | 1.62% | Elevated |
| 20% | 1.40% | 0.76% | 2.16% | Material |
How to read this: A 20% decline in teen engagement directly removes ~1.4% of total time-spent. The additional ~0.76% reflects adult engagement that is mechanically tied to algorithm features originally engineered around teen behaviour (Reels recommendation loops, infinite scroll, engagement notifications). The combined 2.16% total decline is the number that matters for ad inventory pricing.