Too soon to call; Making EPO

Wall Street may have jumped to conclusions last week when investors rewarded Amgen Inc. and punished Transkaryotic Therapies Inc. after a Markman hearing in AMGN's erythropoietin patent infringement suit against TKTX and partner Aventis Pharmaceuticals.

TKTX finished the week down 29 percent at $55.625, losing $506 million in market cap, after a federal judge adopted modified versions of AMGN's definitions of four disputed patent claim terms. AMGN, which is defending the franchise of its blockbuster Epogen product, gained 12 percent to $61.375...