FDA Windfall Over? Rare Obesity Stock Loses $500 Billion in a Day

Rhythm Pharmaceuticals, Inc. (NASDAQ: RYTM), a developer of rare obesity treatments, saw its stock plunge 7.51% to $75.75 by the close of trading on March 27 (Eastern Time). The company’s market capitalization stands at approximately $5.17 billion (roughly KRW 7 trillion), and about $360 million (around KRW 500 billion) was wiped out in a single day, with trading volume topping 1.1 million shares.

On March 20, Rhythm secured its first approved therapy when the U.S. Food and Drug Administration granted approval for IMCIVREE in the “acquired hypothalamic obesity” indication. Since that approval, the stock has been on a roller-coaster ride amid a “sell-the-news” reaction. In early March, Canaccord Genuity trimmed its price target slightly from $141 to $140 but kept a “buy” rating, noting that the company’s long-term growth story remains intact.

Headquartered in Boston, Rhythm Pharmaceuticals is a biopharmaceutical company specializing in pathway-based obesity treatments for rare genetic forms of obesity caused by MC4 receptor pathway defects and hypothalamic injury. Its lead product, IMCIVREE, has already been approved in the U.S. and Europe for weight management in patients with rare genetic obesity disorders—including Bardet-Biedl syndrome and POMC, PCSK1 or LEPR deficiencies.