K-pop boy band BTS has climbed to the top of U.S. Billboard charts, appeared on the Tonight Show Starring Jimmy Fallon and is in the middle of a sell-out world tour that’s taking them through 12 countries, including the U.S. and England.

But while the energetic dance group may be riding high, other K-pop stars are finding it harder to reach global stardom in a crowded field. Shares of JYP Entertainment Corp., the agency behind girl group "Twice," slid a record 20 percent in Seoul Wednesday after an analyst said the company is likely to miss earnings estimates. That spurred declines in other agencies too.

"The downgrade in the analyst’s estimates is sparking a selloff by investors who want to profit take," said Lee Seung Hoon, head of equities at DB Asset Management in Seoul. "The sector was the only one in Korea’s stock market that rallied despite the recent rout."

The $4.7 billion K-pop industry is one of South Korea’s largest cultural exports, and the talent agencies were among the best stock performers in Asia this year. Their gains came crashing down on Wednesday, after Hana Financial Investment Co. analyst Kihoon Lee said new bands may not be as successful as recent groups.

Lee lowered his third-quarter operating profit estimate for JYP, which was worth more than $1 billion in market value yesterday, by 20 percent from his previous estimate, citing an increase in production costs and smaller-than-expected revenue from fan-meeting events.

YG Entertainment Inc., manager of girl group “Black Pink,” fell as much as 12 percent, while SM Entertainment Co. dropped as much as 15 percent. The declines were the worst for the stocks since at least 2012. BTS is represented by privately-held Big Hit Entertainment Co.

— With assistance by Sohee Kim, and Jihye Lee