Company: SION
Filing Date: 2025-11-05
Form Type: 10-Q
Source: 0001628280-25-049251
Chunk: 336

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-11-05
Form: 10-Q
Item: Part II, Item 8
Chunk 336
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. In September 2025, the FASB issued ASU 2025-07, Derivatives Scope Refinement, ("ASU 2025-07"). ASU 2025-07 creates a scope exception within ASC 815 for certain contracts with underlyings tied to a party's operations or activities (such as regulatory approval, clinical, or earnings milestones), which may cause some 

F-8

arrangements that previously met the derivative definition to no longer be accounted for as derivatives. The guidance is effective for fiscal years beginning after December 15, 2026, including interim periods, early adoption is permitted. Entities may adopt prospectively for new or modified contracts after the adoption date, or modified retrospectively for contracts outstanding at adoption with a cumulative-effect adjustment to opening retained earnings.  The Company expects to adopt prospectively and does not expect a material impact, though this guidance may affect the accounting for future milestone-linked arrangements executed after adoption. Tax Law ChangesOn July 4, 2025, the United States Congress passed budget reconciliation bill H.R. 1, referred to as the One Big Beautiful Bill Act (“H.R. 1”), which introduced changes to U.S. federal tax law. A key provision of H.R. 1 includes a modification to the treatment of research and development ("R&D") expenditures under Section 174. As a result of the new legislation, the Company recorded a one-time adjustment in the third quarter of 2025 to expense the remaining unamortized R&D balance. The corresponding deferred tax impact was fully offset by the Company’s valuation allowance, and therefore did not result in a material impact on the Company’s financial results for the period.

3. Marketable Securities 

The following tables summarize the amortized cost and estimated fair value of the Company’s current and noncurrent marketable securities (in thousands):September 30, 2025AmortizedCost UnrealizedGainsUnrealizedLosses Fair ValueMarketable securities, current:U.S. Treasury securities$130,095 $213 $— $130,308 Commercial paper28,989 2 (5)28,986 Government agency securities24,477 22 — 24,499 Corporate debt13,701 5 (1)13,705 Total marketable securities, current197,262 242 (6)197,498 Marketable securities, noncurrent:U.S. Treasury securities57,128 172