Company: SION
Filing Date: 2025-02-07
Form Type: 424B4
Source: 0001193125-25-022709
Chunk: 143

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-02-07
Form: 424B4
Chunk 143
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 primarily due to our net loss of $45.8 million and changes in operating assets and liabilities of $6.2 million, partially offset by $11.0 million of non-cashcharges related to non-cashlicense expense, stock-based compensation, depreciation, non-cashoperating lease expense and amortization of discounts on marketable securities. 104

For the nine months ended September 30, 2023, net cash used in operating activities was
$36.2 million primarily due to our net loss of $35.4 million and changes in our operating assets and liabilities of $3.9 million, partially offset by $3.0 million of non-cash charges
related to stock-based compensation, depreciation and amortization of discounts on marketable securities.

For the year ended December 31,
2023, net cash used in operating activities was $43.7 million primarily due to our net loss of $47.3 million and changes in operating assets and liabilities of $0.8 million, partially offset by $4.4 million of non-cash charges related to stock-based compensation, depreciation, non-cash operating lease expense and amortization of discounts on marketable securities.

For the year ended December 31, 2022, net cash used in operating activities was $36.1 million primarily due to our net loss of
$40.2 million and changes in our operating assets and liabilities of $2.7 million, partially offset by $1.4 million of non-cash charges related to stock-based compensation, depreciation and
amortization of discounts on marketable securities.

Investing Activities

Net cash used in investing activities was $142.1 million during the nine months ended September 30, 2024, which was primarily driven by
purchases of marketable securities of $175.6 million, partially offset by maturities of marketable securities of $33.5 million.

Net cash
provided by investing activities was $20.2 million during the nine months ended September 30, 2023, which was primarily driven by maturities of marketable securities of $44.8 million, partially offset by purchases of marketable
securities for $23.5 million and purchases of property and equipment of $1.0 million.

Net cash provided by investing activities was
$27.4 million during the year ended December 31, 2023, which was primarily driven by maturities of marketable securities of $52.0 million, partially offset