The latter set of figures is expected to reach 1,500 in 35 states by the end of 2017. More significant, the MinuteClinic facilities will, more often than not, adjoin, complement or closely align themselves with individual CVS drug store ­locations. But in this case the numbers are less important than the synergies this organization has been able to create and develop. Caremark has emerged from a three-year transition period as the most impactful, if not the largest, PBM in the United States. It is currently second among PBMs in volume, behind Express Scripts, with anticipated 2012 sales of $54.7 billion. More to the point, it has a client retention rate of somewhere around 96%, while attracting far more new customers annually than it loses. But what makes Caremark special is the ability it has developed to utilize both its CVS drug store network and its MinuteClinic facilities for the benefit of its customers.