A solicitation and an offer to buy shares of Immunomedics will be made only pursuant to an offer to purchase and related materials that Gilead intends to file with the SEC. At the time the tender offer is commenced, Gilead will file a Tender Offer Statement on Schedule TO with the SEC, and Immunomedics will file a Solicitation/Recommendation Statement on Schedule 14D-9 with the SEC with respect to the tender offer. IMMUNOMEDICS' STOCKHOLDERS AND OTHER INVESTORS ARE URGED TO READ THE TENDER OFFER MATERIALS (INCLUDING AN OFFER TO PURCHASE, A RELATED LETTER OF TRANSMITTAL AND CERTAIN OTHER TENDER OFFER DOCUMENTS) AND THE SOLICITATION/RECOMMENDATION STATEMENT BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION WHICH SHOULD BE READ CAREFULLY BEFORE ANY DECISION IS MADE WITH RESPECT TO THE TENDER OFFER.