Amortization and depreciation
We amortize the capitalized costs associated with the acquisition of players' registrations. These costs are amortized over the period of the employment contract agreed with a player. If a player extends his contract prior to the end of the pre-existing period of employment, the remaining unamortized portion of the acquisition cost is amortized over the period of the new contract. Changes in amortization of the costs of players' registrations from year to year and period to period reflect additional transfer fees paid for the acquisition of players, the impact of contract extensions and the disposal of players' registrations. As such, increased players' registration costs in any period could cause higher amortization in that period and in future periods and have a negative impact on our results of operations. Moreover, to the extent that the player registration costs vary from period to period, this may drive variability in our results of operations.
Depreciation primarily reflects a straight-line depreciation on investments made in property, plant and equipment. Depreciation over the periods under review results primarily from the depreciation of Old Trafford and in recent years from improvements to Old Trafford completed at the beginning of the 2006/07 season and incremental improvements made to Old Trafford over each of the subsequent seasons