The London-listed group has asked its advisers to renew its bid effort, the source said, almost four months after Baxalta rejected an unsolicited $30 billion offer that it said significantly undervalued the company. Shire's bid preparations come three weeks after it announced its $5.9 billion purchase of U.S. rare disease specialist Dyax Corp on the offer which could be structured in cash and shares, the source said, cautioning that no deal was certain and negotiations could still fall through.