A single account has invested $5,200 on Polymarket, betting that the NCAA March Madness Live app will become the #1 Free App in the US App Store on March 20. The current probability of this outcome is 64%. The NCAA Men's Basketball Tournament, known as "March Madness," is a major event in the US, with the first round games starting on March 19. Polymarket has also announced over $2 million in liquidity subsidies for related markets and introduced a new market maker rebate mechanism.