Alexion Pharmaceuticals (NASDAQ:ALXN) continued to show top-line growth in its second quarter report issued last week. The company beat analyst expectations for the quarter and raised 2012 outlook. The stock set a new 52-week high of $109.14 in the days after ALXN’s 2012 guidance was raised. Today, however, the company is trading up 5% on rumors of a takeover bid from Roche (OTC:RHHBY), purportedly at $128 per share, an 18% premium to the current share price that would value the company at $24B. Although strictly rumored, a bid price that high for a company valued around $3B in 2009 would be unprecedented. Alexion has one product on the market, Soliris, for the treatment of ultra-rare paroxysmal nocturnal hemoglobinuria, that costs about $500,000 annually.