Mobile shoppers are out in force this holiday season. After sifting through terabytes of transactional data from about 800 U.S. retail websites, IBM found that Black Friday deals on smartphones and tablets accounted for 21.8 percent of total online sales, an increase of nearly 43 percent from last year.

“We’re off to an incredibly fast start this holiday season as retailers and consumers meet at the intersection of cloud, mobile and social platforms to both offer and take advantage of the best deals,” said Jay Henderson, the head of strategy for IBM’s Smarter Commerce group. “This year’s winners will be those that can deliver seamless experiences to consumers wherever, whenever and however they choose to shop.”

While brick-and-mortar stores reported smaller crowds the day after Thanksgiving, online retailers saw revenue jump by 18.9 percent over the same period in 2012. This massive surge can be credited in large part to improved customer engagement, with retail app installations growing 23 percent year-over-year.

As a result, mobile traffic soared 34 percent to nearly 40 percent of all online activity, according to IBM. Smartphones accounted for 24.9 percent of traffic but only 7.2 percent of all online sales, whereas tablets users made twice as many purchases but consumed only half the bandwidth. Buyers spent an average of $132.75 per order, 15 percent more than smartphone users. Meanwhile, iOS accounted for 28.2 percent of all traffic and 18.1 percent of online sales, while Android came in at 11.4 and 3.5 percent, respectively. Apple users emerged as savvier shoppers across the board, having spent an average of $127.92 per order versus $105.20.

Social media also played a big part in driving Black Friday sales. Holiday shoppers referred from Pinterest shelled out about $92.51, while Facebook referrals averaged $52.30 with nearly four times the conversion rate.