Does Apple's sales slump mean the firm has finally peaked?

The company's $1tn valuation has fallen 20% and fewer people are buying its iPhones

At the start of October Apple was on top of the world. The company had hit a record-breaking valuation of $1tn (770bn), just released its fastest - and most expensive - iPhone and its chief executive, Tim Cook, was hammering rival Facebook over yet another privacy scandal.

Two months on and the shine appears to have worn off the largest company in the world. Its valuation has fallen by nearly 20%. This is partly because key suppliers have issued their own profit warnings, suggesting fewer people are buying the company's phones than expected.