AppLovin (APP) is quietly building an ad behemoth that could step on Amazon's (AMZN) turf. Once primarily known as a mobile game publisher, AppLovin has transitioned into a pure-play software and AI-driven ad tech company. It now acts as an infrastructure layer, connecting thousands of advertisers with mobile app publishers to sell ad space in real time. In a research note, Giarelli points to AppLovin's Rule-of-40 score (a gold-standard metric combining revenue growth and operating margin), which recently clocked in at 151%. BofA expects AppLovin's total revenue in 2026 to reach $9.3 billion, a forecast of nearly 70% growth compared to 2025.