Celgene Corp , which has announced a deal to buy Impact Biomedicines, on Monday forecast 2018 total revenue that fell short of analysts’ estimates, sending the U.S. biotech company’s shares down 2 percent. Celgene, which left its long-range 2020 forecast unchanged, said it expects 2018 full-year revenue of $14.4 billion to $14.8 billion. Analysts’ on average were estimating revenue of $14.83 billion, according to Thomson Reuters I/B/E/S. While headlines suggested the Impact deal announced on Sunday could cost up to $7 billion, Celgene said the only certain cost was the upfront payment of $1.1 billion, with all other payments contingent on approval and major sales milestones for fedratinib, a late stage drug for myelofibrosis.