Soaring artificial intelligence revenues have failed to shield Intel, Amazon and Google’s parent company Alphabet from a brutal Wall Street sell-off, as their latest quarterly results deepened investor jitters over mounting capital spending and delayed returns. Intel plunged about 23 per cent in extended trading on Thursday, while Amazon shed 7.3 per cent. Alphabet tumbled 12.6 per cent during the regular session in its worst day on record, dragging the Nasdaq Composite down 1.4 per cent and...