Phathom Pharmaceuticals Inc

The information set forth below is included herein for the purpose of providing the disclosure required under “Item 2.05 Costs Associated with Exit or Disposal Activities.” and “Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.” of Form 8-K.

On April 29, 2025, our board of directors (the “Board”) approved a restructuring to reduce cash burn and focus on commercial execution. We have decided to reduce investment in direct-to-consumer promotion and will suspend, defer, or slow several clinical and product development programs, including deferring the start of the Phase 2 eosinophilic esophagitis (EoE) trial.

In connection with this restructuring, we expect to reduce our workforce by 28 employees, or approximately 6%. We expect to incur one-time costs of approximately $7 million to $10 million in connection with the workforce reduction. The majority of these expenses will be recognized in the second quarter of 2025.These costs consist primarily of cash expenditures related to one-time termination benefits (some of which are contractual), including severance, healthcare and related benefits, and other estimated non-cash expense. We estimate that the workforce reduction will be substantially completed in the second quarter of 2025. The estimate of costs that we expect to incur and the timing thereof are subject to a number of assumptions, and actual results may differ materially. We may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the actions described above.

In addition, as part of the restructuring, we announced certain leadership changes. Azmi Nabulsi, M.D., our Chief Operating Officer and Molly Henderson, our Chief Financial Officer, ceased serving in these positions at the company, effective April 30, 2025, and will continue as non-executive employees through May 16, 2025. Effective May 1, 2025, we designated Robert Breedlove, our Vice President of Finance, as our principal financial officer and principal accounting officer for purposes of financial reporting under the Securities Exchange Act of 1934, as amended, replacing Ms. Henderson in such roles.

Robert Breedlove, 33, has served as our Vice President of Finance since October 2021. From March 2019 to October 2021, Mr. Breedlove served as Senior Manager at van den Boom & Associates, an accounting consulting firm. He worked for NeoGenomics, Inc. from October 2017 to March 2019 as Manager of Financial Reporting and Compliance. Mr. Breedlove began his career at Ernst &

Young where he served in roles of increasing responsibilities from 2012 to 2017. Mr. Breedlove is a Certified Public Account and received his B.A. and M.A. in accountancy from the University of San Diego.

In connection with their separations, we expect to enter into transition agreements with each of Dr. Nabulsi and Ms. Henderson wherein we will provide them with the severance benefits payable under their employment agreements, as well as an extension of the post-termination exercise period of their vested stock options. The separation agreements will include a release of claims in favor of the company and the severance benefits will be subject to their continued compliance with post-termination restrictive covenants.

Director and Officer Trading Arrangements:

Rule 10b5-1 Trading Plans

From time to time, our officers (as defined in Rule 16a-1(f) of the Exchange Act) and directors may enter into Rule 10b5-1 or non-Rule 10b5-1 trading arrangements (as each such term is defined in Item 408 of Regulation S-K). During the three months ended March 31, 2025, none of our officers or directors adopted, modified orterminated any such trading arrangements.