X0202 SCHEDULE 13G 0001224962 XXXXXXXX LIVE Common Stock, $0.001 par value 04/30/2026 0001540171 Avalyn Pharma Inc. 05348Y105 105 W First Street Boston MA 02127 Rule 13d-1(c) Perceptive Advisors LLC b DE 0 2675296 0 2675296 2675296 N 6.0 IA Joseph Edelman b X1 0 2675296 0 2675296 2675296 N 6.0 IN Perceptive Life Sciences Master Fund, Ltd. b E9 0 425000 0 425000 425000 N 1.0 CO Perceptive Xontogeny Venture Fund II, L.P b DE 0 2250296 0 2250296 2250296 N 5.1 PN Avalyn Pharma Inc. 105 W FIRST ST., BOSTON, Massachusetts 02127 The names of the persons filing this report (collectively, the "Reporting Persons") with respect to the Common Stock, $0.001 par value per share (the "Common Stock") of Avalyn Pharma Inc. (the "Issuer") are: (i) Perceptive Advisors LLC ("Perceptive Advisors") (ii) Joseph Edelman ("Mr. Edelman") (iii) Perceptive Life Sciences Master Fund, Ltd. (the "Master Fund") (iv) Perceptive Xontogeny Venture Fund II, LP ("PXV II") The address of the principal business office of each of the Reporting Persons is: 51 Astor Place, 10th Floor, New York, NY 10003 Perceptive Advisors is a Delaware limited liability company. Mr. Edelman is a United States citizen. The Master Fund is a Cayman Islands corporation. PVX II is a Delaware limited partnership. Y The information required by this item with respect to each Reporting Person is set forth in Rows 5 through 9 and 11 of the cover pages to this Schedule 13G. The ownership percentages are based on 44,312,047 shares of Common Stock outstanding, as reported by the Issuer in its prospectus filed pursuant to Rule 424(b)(4) with the Securities and Exchange Commission on April 30, 2026, giving effect to the underwriters' exercise of their over-allotment option. The Master Fund directly holds 425,000 shares of Common Stock and PXV II directly holds 2,250,296 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund and may be deemed to beneficially own shares held by the Master Fund. Perceptive Venture Advisors, LLC is the investment manager of PXV II and is controlled by Perceptive Advisors, who may be deemed to beneficially own the shares held by PXV II. Perceptive Xontogeny Ventures II GP, LLC is the general partner of PXV II. Mr. Edelman is the managing member of Perceptive Advisors and may be deemed to beneficially own the shares held by the Master Fund and PXV II. Perceptive Advisors: 6.0% Mr. Edelman: 6.0% Master Fund: 1.0% PXV II: 5.1 Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0 PXV II: 0 Perceptive Advisors: 2,675,296 Mr. Edelman: 2,675,296 Master Fund: 425,000 PXV II: 2,250,296 Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0 PXV II: 0 Perceptive Advisors: 2,675,296 Mr. Edelman: 2,675,296 Master Fund: 425,000 PXV II: 2,250,296 Y Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. Exhibit 99.1 - Joint Filing Agreement Perceptive Advisors LLC /s/ Joseph Edelman 05/07/2026 Joseph Edelman /s/ Joseph Edelman 05/07/2026 Perceptive Life Sciences Master Fund, Ltd. /s/ Joseph Edelman 05/07/2026 Perceptive Xontogeny Venture Fund II, L.P /s/ Joseph Edelman 05/07/2026