Nasdaq CF New Drug Major Shareholder Continues to Sell 50 Billion Won Stake

Between mid-April and early May, OrbiMed Advisors, a major shareholder of Nasdaq-listed biotechnology company Sionna Therapeutics, Inc. (SION), executed a pre-established Rule 10b5-1 trading plan in the open market. Over that period, it sold more than 800,000 shares, raising roughly $36 million (approximately KRW 50 billion).

Following these transactions, the indirect stake held by OrbiMed’s affiliated funds declined to about 6.6% of Sionna’s outstanding shares. In its public filing, OrbiMed noted that, as a financial investor, it may continue to buy or sell shares depending on market conditions but does not intend to take an active role in the company’s governance or capital structure—despite its board representation and contractual rights.

On April 27, Sionna Therapeutics announced the completion of enrollment in its PreciSION CF Phase 2a trial of NBD1 stabilizer SION-719 in patients with cystic fibrosis. In its March 2 financial report, the company disclosed it held approximately $310.3 million (about KRW 430 billion) in cash and cash equivalents, securing operating funds through 2028.

Sionna Therapeutics is a clinical-stage biotech focused on developing CFTR modulators for cystic fibrosis treatment. The company went public on Nasdaq in February 2025. Global healthcare investment firm OrbiMed participated as an early investor via one of its private funds and currently has a representative on Sionna’s board to monitor management.