SAN FRANCISCO (MarketWatch) - Amazon.com reported an 8% rise in fourth-quarter earnings as sales rose 36% for the period. For the quarter ended Dec. 31, Amazon [s:amzn] reported net income of $416 million, or 91 cents a share, compared to net income of $384 million, or 85 cents a share, for the same period the previous year. Sales jumped by 36% to $12.95 billion. Analysts were expecting earnings of 88 cents a share on revenue of $13 billion, according to consensus estimates from FactSet Research.