TOKYO (AP) ¿ Dainippon Sumitomo Pharma Co. is acquiring U.S. drug maker Sepracor Inc., which makes insomnia drug Lunesta, for about $2.6 billion in an effort to expand in the U.S. market, both sides said Thursday. The Japanese drug maker said the deal will give it access to Sepracor's established sales network of about 1,325 people in the U.S., which will help it establish a sales platform for lurasidone, a potential treatment for schizophrenia that is now in late-stage trials. Dainippon said it plans to submit a new drug application for lurasidone to the U.S. Food and Drug Administration in early 2010. Dainippon said that the acquisition of Sepracor will also increase its overseas revenue to 40 percent of its total. The Osaka-based company has depended on its own domestic market up until now. The company said it will offer $23 per share, a 27.6 percent premium over Sepracor's closing price Tuesday, through a tender offer set to start in early September. The deal is expected to close during the fourth quarter. Shares of Sepracor had soared 26 percent, to $22.80 on Wednesday afternoon, amid media reports in Japan that a deal was imminent. In midday trading on Thursday, Sepracor changed hands at $22.82. In Japanese trading Thursday, Dainippon's shares closed up at 1.2 percent to 1,025 yen.