Shares of genetics firm Illumina (ILMN) tumbled 9% in early trading Monday after Roche's (RHHBY) chairman said it was "off the table" as a buyout target. Meanwhile, Illumina made another buyout of its own. Over the weekend, Swiss newspaper SonntagsZeitung published an interview with Franz Humer in which the chairman said merger negotiations had broken down over price. Illumina turned down Roche's $6.8 billion bid in April, but last month its stock