Digital or analogue clock? Probably digital with a new item but if it happened to be an analogue clock there could be a fault in the mechanism, a tightness causing it to slow a little.

In the case of a digital clock - it might be driven in the traditional way of using the AC mains frequency of 50Hz (UK and Europe) or 60Hz (USA) and in that case a loss of a couple of minutes per day means either the mains frequency where you are is slightly less than 60Hz or the sine wave of your mains supply is carrying electrical interference and confusing the clock. This can also happen with the analogue type. The alternative, if the mains are clean and being delivered at exactly 60Hz, the alternative assumption would be either a circuitry fault or cheap and nasty circuitry...

The other type of digital clock is driven/regulated by quartz circuitry and as we all know, if a quartz clock doesn't keep near-perfect time when it is new - there is something wrong with it.