OrbiMed Amends Plan to Sell $9 Million in Sionna Therapeutics Stock
SION has more than doubled off its 52-week low of $13.255.
Summary
OrbiMed, a major institutional investor, filed an amended Form 144 to sell $9.03 million in Sionna Therapeutics stock, continuing a pattern of significant share distribution.
Key Events · Ownership and Investor Activity · SION
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Amended Intent to Sell Shares
OrbiMed Private Investments VIII, LP, a major institutional investor, filed an amended Form 144 to sell 210,876 shares of common stock, valued at approximately $9.03 million.
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Ongoing Share Distribution
This filing is part of a broader pattern of share distribution by OrbiMed, which has already sold 858,981 shares for gross proceeds of $38.79 million over the past three months.
Analysis · SION · Life Sciences
OrbiMed Private Investments VIII, LP, a significant institutional investor, has filed an amended Form 144 indicating its intent to sell an additional $9.03 million worth of Sionna Therapeutics common stock. This follows previous filings and a pattern of substantial share distribution by OrbiMed, totaling over $38.7 million in sales over the past three months. This ongoing selling activity by a major shareholder could create an overhang on the stock.
How filings like this one have moved
In the 30 days to Sep 23, 2026, 29.1% of the 1683 measured filings Wiseek scored 7 moved their stock by 5% or more by the next session's close. The median move was -0.32%. These are measured outcomes after filings of this importance, not a forecast for this one.
Measured one observation per ticker per day, after exclusions. Current figures: Filing Impact Tracker · open dataset
At the time of this filing, SION was trading at $41.10 on NASDAQ in the Life Sciences sector, with a market capitalization of approximately $1.9B. The 52-week trading range was $13.26 to $48.45. This filing was assessed with negative market sentiment and an importance score of 7 out of 10.