Investors appear reassured by the company's potential growth prospects, given its record full-year revenue and its acquisition of a rival energy drink brand.

Energy drink maker Celsius is paying $1.8 billion to buy rival Alani Nu, a brand that has been propelled by social-media influencers and pitches itself as a low-cal fitness aid.

The purchase allows Celsius to add a fast-growing beverage popular with young women while better positioning it to compete against rivals Red Bull and Monster.