(Image source: mainjustice.com) Pfizer Inc. (NYSE:PFE) shares are climbing higher in the early session after it was revealed that the pharmaceutical giant bid nearly $100 billion at the top of the year to acquire its rival AstraZeneca plc (LON:AZN). Despite being turndown twice by AstraZeneca, Pfizer plans on continuing it pursuit. M&A is red hot in the health care sector. Every other week the industry is announcing a merger or sale. At this rate, maybe AstraZeneca will relent.