This excerpt taken from the CVS 10-K filed Feb 27, 2007.
Charges to earnings resulting from the application of the purchase method of accounting may adversely affect the market value of our common stock following the merger.
In accordance with U.S. GAAP, we will be considered the acquiror for accounting purposes. We will account for the merger using the purchase method of accounting, which will result in charges to our earnings that could adversely affect the market value of our common stock following the completion of the merger. Under the purchase method of accounting, we will allocate the total purchase price to the assets acquired and liabilities assumed from Caremark based on their fair values as of the date of the completion of the merger, and record any excess of the purchase price over those fair values as goodwill. For certain tangible and intangible assets, reevaluating their fair values as of the completion date of the merger will result in our incurring additional depreciation and/or amortization expense that exceed the combined amounts recorded by CVS and Caremark prior to the merger. This increased expense will be recorded by us over the useful lives of the underlying assets. In addition, to the extent the value of goodwill or intangible assets were to become impaired, we may be required to incur charges relating to the impairment of those assets.