Shareholder rights law firm Robbins LLP is investigating Sionna Therapeutics (NASDAQ: SION) to determine whether certain Sionna Therapeutics officers and directors violated securities laws and breached fiduciary duties to shareholders.

Why Are We Investigating Sionna Therapeutics?

On Monday, August 10, 2026, Sionna Therapeutics stock plunged 92% to close at $4.51 after the Company reported disappointing results from its Phase 2a proof-of-concept study of SION-719 in cystic fibrosis.

According to media reports, the PreciSION CF trial failed to achieve its key activity endpoint, which measured the reduction in sweat chloride – a key marker of treatment success – when SION-719 was administered alongside the standard-of-care treatment Trikafta.

Though the Company finished the second quarter with "substantial financial resources," it intends to take measures to preserve capital while determining the appropriate path forward for its clinical pipeline.

What Can Shareholders Do Now?

If you lost money investing in Sionna Therapeutics contact Robbins LLP for more information by submitting an inquiry, emailing attorney Aaron Dumas, Jr., or calling (800) 350-6003.

All representation is on a contingency fee basis. Shareholders pay no fees or expenses.

About Robbins LLP

A recognized leader in shareholder rights litigation, the attorneys and staff of Robbins LLP have been dedicated to helping shareholders recover losses, improve corporate governance structures, and hold company executives accountable for their wrongdoing since 2002. Since our inception, we have obtained over $1 billion for shareholders.

To be notified if a class action against Sionna Therapeutics settles or to receive free alerts when corporate executives engage in wrongdoing, sign up for Stock Watch today.

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Robbins LLP is investigating Sionna Therapeutics (NASDAQ: SION) to determine whether certain Sionna Therapeutics officers and directors violated securities laws and breached fiduciary duties to shareholders.