Line Corp. posted its biggest drop yet as analysts cut ratings after fourth-quarter profit and revenue that missed estimates.

The stock finished more than 10 percent lower at ¥3,755 in Tokyo on Thursday, the steepest decline since listing in July. Line's operating profit of ¥1.6 billion ($14 million) in the quarter ended Dec. 31 was less than the ¥5.34 billion average of analysts' projections compiled by Bloomberg. Sales reached ¥37.5 billion in the period, short of the predicted ¥38.7 billion.

Chief Executive Officer Takeshi Idezawa is under pressure to build on the 20-plus percent share price gain since the initial public offering in July. As user growth and revenue from games and digital stickers slows, the company has to come up with new ways to make people spend on what is otherwise a free messaging service. For now, Line has pinned its hopes on advertising growth as analysts project profit and sales to climb.