BTS took a bold but necessary gamble with 'Swim,' Karlsson says

Swedish songwriter and producer Alex Karlsson has spent more than a decade helping shape the sound of K-pop from behind the scenes.

Since beginning his collaboration with SM Entertainment in 2013, Karlsson has infused elements of Swedish pop songwriting into numerous K-pop releases.

His credits span some of the industry's biggest acts, including BTS' "We Are Bulletproof: The Eternal," SuperM's "Tiger Inside," Enhypen's "Fever," Tomorrow X Together's "Loser=Lover" and Ateez's "Bouncy (K-Hot Chill ...