Biogen (NASDAQ: BIIB) , Groupon (NASDAQ: GRPN) , and Omeros (NASDAQ: OMER) were among the worst performers on the day. Investors had initially feared the return of inflationary pressure after this morning's CPI report from the Labor Department, but despite higher bond yields, market participants ended up paying little attention to the implications and instead bid up stock indexes. The e-commerce company best known for its once-groundbreaking daily deals business said that gross billings fell 2%, fueling a 4% drop in revenue and resulting in adjusted earnings that didn't live up to expectations .