With 480 million products available to purchase on Amazon's U.S. marketplace, some wonder how the marketplace ranks its results. Sales performance carries significant weight, but Business Insider points to a study from Ripen eCommerce that suggests there is no one factor that determines location on a product's search ranking. The findings suggest that Amazon weights search performance in favor of its own products and programs. If Amazon owns a particular product, or if that product is eligible for Amazon Prime delivery, then it typically ranks higher in search results than products fulfilled by third-party brands, according to Andrew Meola.