Investors are better served ignoring the market's monthly whims and whispers and focusing instead on discovering stocks with long term tailwinds.

In biopharma, that means keeping an eye on drug spending trends, which measure both drug prices and total prescription volume, and patient population forecasts, which provide insight into whether the market for drug treatment is likely to grow or shrink.

After reviewing Express Scripts' annual drug spending trend report, one disease category stands out for both its significant current spending and its potential for future growth. That category is expected to post double digit growth in spending in each of the next three years, providing significant revenue opportunity for Sanofi (SNY 1.15%) and Merck (MRK -0.05%)

In the following slideshow you'll learn what this one big drug spending trend is and how rapid growth in treating one of the most prevalent diseases in America may drive Sanofi and Merck's shares higher.