ABSTRACK
This study investigates the impact of viral marketing on the purchase decisions for iPhones at Yusroneiphone.id. It centers on how “For You Page” (FYP) viral content on the brand’s social media drives consumer behavior—especially important given evolving market dynamics and increasingly diverse consumer preferences.

Using a quantitative approach, data was collected via Google Form questionnaires distributed to followers of Yusroneiphone.id on Instagram and to in-store buyers. Analysis was performed using SmartPLS (Partial Least Squares), focusing on three characteristics of viral marketing: quantity of information, quality of argument, and source credibility.

Findings indicate that effective viral marketing hinges on delivering sufficient quantity of information and maintaining strong source credibility, both of which significantly enhance consumer trust and influence purchase decisions. Conversely, the quality of argument in the viral content did not show a significant effect on the iPhone purchasing behavior at Yusroneiphone.id. The study recommends that the company focus more on disseminating abundant, trustworthy information in its viral marketing strategies to better drive purchase decisions amid intense competition.

Keywords: Quantity of Information, Quality of Argument, Source Credibility, Purchase Decision