Feb 28 (Reuters) - Vivani Medical shares surged more than five-fold in early trading on Wednesday after the drug developer said its experimental under-the-skin drug implant helped reduce weight in obese mice in a pre-clinical trial.

The implant caused a weight loss of about 20% compared to a sham treatment in high-fat diet-induced obese mice after a 28-day treatment, the company said.

Weight-loss drugmakers have emerged as a hot favorite among investors since the launch of new powerful treatments from Novo Nordisk and Eli Lilly. The global market for such drugs is expected to reach at least $100 billion by the end of the decade.

Vivani, which had a market value of $51 million as of Tuesday's close, also said another implant, being developed for the treatment of type 2 diabetes, reduced weight in healthy rats in a different trial.

The Alameda, California-based company's third experimental implant for humans, also for obesity, is being tested in pre-clinical trials.

Vivani is set to add as much as $398 million to its market cap if gains hold. (Reporting by Puyaan Singh in Bengaluru; Editing by Sriraj Kalluvila)