[MrRumblefish]

Stocks are (usually) bought based on future earnings potential. So for an oil company, whilst oil is needed, it is unlikely to suddenly make a huge profit over the other oil companies and instead will provide relatively safe long term returns.

So its price reflects this both good and bad stability.

On the other hand Apple has a track record of coming up with almost totally new markets which it can dominate and take the lions share of the profit, or find a niche to exploit in an existing market - ala iPhone. So it's price is speculating that they can keep finding these huge new profits in addition to the huge profits they already make.

tl;dr Apple is like a giant profit finding machine.