Material Event (Form 8-K)

As previously disclosed by GATX Corporation ("GATX" or the "Company"), including in the Company's Current Report on Form 8-K filed on January 5, 2026, as amended by the Company's Form 8-K/A filed on March 3, 2026, GATX holds a 30% interest in GABX Leasing LLC (the "JV"), with the remaining 70% held indirectly through GABX Leasing Holding LLC ("Blocker") by Michigan U.S. Holdings LP, an affiliate of Brookfield Infrastructure Partners L.P. and its institutional partners (collectively, "Brookfield"). Pursuant to that certain Call Option Agreement among GATX, the JV and Michigan U.S. Holdings LP (filed as Exhibit 10.4 to the January 5, 2026 Form 8-K), GATX has a series of call options that, if exercised in full, would result in GATX owning 100% of the JV through purchases of interests in Blocker.

On June 30, 2026, GATX exercised its first call option under the Call Option Agreement to acquire an interest in Blocker, thereby indirectly increasing GATX's interest in the JV to approximately 33.535%. In connection with the exercise, the limited liability company agreement of Blocker was amended and restated (the "A&R Blocker LLC Agreement") to, among other things, admit GATX as a member; grant GATX joint approval rights over specified fundamental actions (including, among other things, amendments, equity issuances, indebtedness, capital calls, and major transactions), and update related governance, capital (including funding mechanics), and transfer provisions. The A&R Blocker LLC Agreement further provides that Brookfield will continue as Managing Member under such agreement unless and until GATX owns 100% of the outstanding units of Blocker.

The foregoing description of the A&R Blocker LLC Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the A&R Blocker LLC Agreement, a copy of which is filed as Exhibit 10.1 to this Current Report on Form 8-K and incorporated herein by reference.