By Alistair Barr

SAN FRANCISCO (Reuters) - Amazon.com Inc shares jumped almost 7 percent on Tuesday after the world's largest Internet retailer reported quarterly results.

The company said fourth-quarter revenue jumped 22 percent to $21.27 billion as it grabbed a big share of online spending during the crucial holiday period.

The Seattle-based company also reported net income of $97 million, or 21 cents a share in the fourth quarter, compared with $177 million, or 38 cents a share in the same period a year earlier.

Operating income jumped 56 percent to $405 million in the fourth quarter, compared with $260 million in the fourth quarter of 2011, Amazon also said.

Amazon shares climbed 6.8 percent to $278 in after-hours trading following its results.

(Reporting By Alistair Barr; Editing by Bernard Orr)