Imagine Dragons' "Thunder" (KidinaKorner) is the new #1 at Top 40 this week, but that could be a brief victory, since the Greatest Gainer is Camilla Cabello's "Havana" f/Young Thug (SYCO/Epic) and she is leaping to the top of the chart very quickly, moving from #7 to #3 this week. Halsey's "Bad At Love" (Astralwerks/Capitol) moves up inside the Top 10. Post Malone's "Rockstar" f/ 21 Savage (Republic) joins the Top 15. Calvin Harris' "Faking It" f/ Kehlani & Lil Yachty (Columbia) climbs into the Top 20. And joining the chart this week is Taylor Swift's "End Game" f/ Ed Sheeran & Future (Big Machine/Republic).