X0609 4 2026-05-21 0001420565 Rein Therapeutics, Inc. RNTX 0001007706 VON RICKENBACH JOSEF H false 12407 N. MOPAC EXPY. SUITE 250 #390 AUSTIN TX 78758 true false false false false Common stock , $0.001 par value 2026-05-21 4 P false 3420 1.0422 A 18874 D Common stock , $0.001 par value 2026-05-22 4 P false 15950 1.0475 A 34824 D Common stock , $0.001 par value 2026-05-26 4 P false 23190 1.0552 A 58014 D Common stock , $0.001 par value 2026-05-27 4 P false 4500 1.0708 A 62514 D The reported shares were purchased in the open market in multiple transactions at prices ranging from $1.05 and $1.035 on May 21, 2026, $1.07 and $1.01 on May 22, 2026, $1.07 and $1.03 on May 26, 2026 and $1.08 and $1.03 on May 27, 2026. The prices reported in Column 4 are a weighted average price for purchase on the respective day. The reporting person undertakes to provide to Rein Therapeutics, Inc., any stockholder of Rein Therapeutics, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote (1). /s/ Josef H. von Rickenbach 2026-05-27