Amazon.com shares fall premarket after fourth-quarter cloud-computing sales and the tech giant’s outlook for the first quarter came below analysts’ expectations. Amazon stock closed 1.1% higher at $238.83 ahead of results Thursday. Shares fell post market and are down 3.8% premarket, touching a low of $229.24. Sales at Amazon Web Services, the group’s cloud-computing unit, grew 19% to $28.79 billion, but missed a FactSet forecast of $28.82 billion. Meanwhile, Amazon guided for sales of between $151 billion and $155.5 billion in the first quarter, with operating profit between $14 billion and $18 billion. Analysts are forecasting net sales of $158.70 billion and operating profit of nearly $18.55 billion for the current quarter, according to FactSet.