Shares of Progenics Pharmaceuticals Inc. dropped 5.5% in premarket trading Wednesday, even though the cancer treatment developer agreed to be acquired by Lantheus Holdings Inc. in an all-stock deal, given the sharp selloff in Lantheus shares. Under terms of the agreement, Progenics shareholders will receive 0.2502 Lantheus shares for each Progenics share they own. Based on Tuesday’s stock closing price of $24.03 for Lantheus and $4.95 for Progenics, the deal would value Progenics shares at $6.01, or a 21.5% premium, and suggest a market capitalization for Progenics of about $519.6 million. But with Lantheus shares plunging 18% toward an 8-month low ahead of the open, the deal would value Progenics’ stock at about $4.93. The companies said the deal is expected to close in the first quarter of 2020, subject to shareholder approval. Progenics shares have gained 17.9% year to date and Lantheus’s stock has climbed 53.6%, while the S&P 500 has advanced 17.3%.Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.