Exhibit 99.1 HALOZYME REPORTS FIRST QUARTER 2024 FINANCIAL AND OPERATING RESULTS Revenue Increased 21% YOY to $196 million; Net Income of $77 million; Adjusted EBITDA of $116 million; GAAP Diluted EPS of $0.60 and Non-GAAP Diluted EPS of $0.791 Royalty Revenue Increased 21% YOY to $121 million Reiterating 2024 Financial Guidance: Total Revenue of $915 - $985 million, Representing YOY Growth of 10% - 19%, Adjusted EBITDA of $535 - $585 million, Representing YOY Growth of 26% - 37% and Non-GAAP Diluted EPS of ...