This excerpt taken from the CVS 10-K filed Feb 27, 2007.
Following the merger our common stock may be affected by factors different from those affecting the price of our common stock historically.
As our business and the business of Caremark are different, our results of operations as well as the price of our common stock following the merger may be affected by factors different than those factors affecting us and Caremark as independent stand-alone entities. Following the merger we will face additional risks and uncertainties not otherwise facing each independent company prior to the merger. For a discussion of certain factors to consider in connection with the combined company, see the below section titled Risks Related to CVS, Caremark and the Combined Company.