San Francisco-based firm Pillsbury Winthrop has secured a coveted lead role on the largest biotechnology merger for a year as further evidence mounts of a revival in the moribund US technology M&A market.

The deal sees Pillsburys act for San Diego’s Idec Pharmaceuticals on the $6.7bn (£4bn) merger with Biogen of Cambridge, Massachusetts. The transaction, which has been structured as a stock-for-stock exchange to create Biogen Idec, is the largest US life sciences deal since Amgen acquired Immunex for $10bn (£6bn) a year ago.