With the first day of fall yesterday, Sept. 23, summer 2015 is officially in the books. K-pop fans will remember it as the most exciting and competitive season in years as the scene welcomed loads of comebacks from some of its most beloved acts. It made for exciting chart battles too as the likes of SHINee and Girls' Generation earned No. 1s on the World Albums chart while BIGBANG locked up three chart-toppers on the World Digital Songs -- tying a record PSY holds -- as hot summer videos racked up millions of views on YouTube.
Using the same date tracking Billboard uses to tally its annual Summer Songs chart (from Memorial Day to Labor Day), we have the 20 biggest K-pop songs this summer and most-viewed videos on YouTube. The top 20 performing songs on the weekly World Digital Songs chart during the summer period (charts dated June 13-Sept. 19, 2015), based on aggregated sales for each title while they were on the chart.