Alvotech's stock surged 5.26% during pre-market trading on Thursday, following the release of its fourth-quarter financial results.

The biopharmaceutical company reported quarterly sales of $173.2 million, which exceeded analyst consensus estimates of $159.927 million by approximately 8.3%. This represents a year-over-year increase of nearly 13% from sales of $153.34 million in the same period last year.

The positive earnings surprise is the primary driver behind the pre-market rally, as investors react favorably to the company's stronger-than-expected financial performance.