A scrap of data on Amgen's obesity drug MariTide wipes out $12 billion in market value

On Tuesday, a tiny scrap of data on Amgen's leading obesity candidate — not yet verified — wiped out $12 billion in market value.

The data, discovered by an analyst at Cantor Fitzgerald, focused on concerns about possible side effects of the drug, called MariTide. After being widely disclosed in an investor note, the company's shares fell 7%, a reminder that the stock is in an extremely precarious position ahead of a critical therapy forecast.

Analyst Olivia Brayer found the previously unreported data in hidden tabs of a file included in the release of early test results for MariTide. The hidden tabs appeared to contain results that showed study participants experienced loss of bone mineral density, particularly in the group taking the highest doses of the drug, Brayer said.