Splitting a planned total discount into multiple smaller stacked pieces (e.g., a base sale price plus a coupon plus a sign-up credit) outperforms offering a single discount of the same total value, per Bentley University research (six experiments, 9,000+ deal posts, published December 2025). Cited effects: 16% higher purchase intent when a 25% discount was split into four stackable parts, plus 66% more views, 53% more upvotes, and 52% more comments on stacked deals versus single-discount equivalents.
Two mechanisms drive the effect: stacking feels rare and 'unlocked' rather than simply given, creating urgency; and the small effort a shopper spends assembling the stacked discount increases how much they value it (an effort-justification effect, similar to needing to complete a task to redeem a coupon).
Caveats: the effect weakens once the total discount is already large (e.g., 65% off), and works best for moderate discounts in the 15-35% range. It also fails if assembling the stack requires too much manual effort from the shopper — the effort must stay small enough to feel like a game, not a chore. Practically, most steps should be automated so the shopper only takes one or two simple actions. Related to Strikethrough Price & Coupon Badge Engineering and Holiday/Event Pricing Strategy.