Smartphones and tablets accounted for most of the traffic to online retail sites during Thanksgiving, according to new IBM figures. It’s the first time mobile devices have surpassed PCs in generating cyber-sales in the seven years IBM has been measuring activity.

Drawing on real-time transactional data from some 8,000 brands around the world, Big Blue found that handhelds generated of 52.1 percent of all activity on Thursday, a few fractions of a percent less than what it anticipated but still enough to set a historic milestone. The mobile tide also lifted engagement on Black Friday, accounting for 49.6 percent of traffic but falling just short of bagging the e-commerce space a double record.

Online retailers can take solace in the fact the increased traffic from smartphones and tablets contributed to a 14.3 percent increase in Thanksgiving sales and a 9.5 percent earnings boost on Black Friday, accounting for over a quarter of total revenue across the two days. Yet even as mobile activity surged, the growth rate declined significantly from last year’s holiday season, which Big Blue attributes not so much to reduced consumer demand but other trends such as the rising use of online coupons.

Seemingly confirming that observation is the fact that the average Thanksgiving order size dropped 1.8 percent from 2013 – a full point less than what IBM expected – while the average purchase on Black Friday was 4.4 percent smaller, on par with the company’s prediction. Coupons seem especially popular among the mobile device owners, with orders from from desktops averaging 16.6 percent larger than mobile deals at $135.33.

That discrepancy is largely the result of the Android dragging down the total: IBM has discovered that the typical user of Google’s mobile operating system spent 24.3 percent less users of Apple iOS devices. Platforms aside, however, tablet owners once again prevailed as the top spenders across-the-board with a 17.6 percent lead in average order size over smartphones and a 35.5 percent greater stake of overall sales – all despite accounting for less than half as much traffic.

Retailers are becoming increasingly sophisticated in how they attract mobile shoppers, making use of e-coupons and social media channels to draw attention to their brands. Those efforts have been paying off, according to IBM, with Facebook and Pinterest referrals both driving purchases averaging above $100.

Retailers in the health and beauty category appeared to have been the most successful in attracting consumers’ attention: Big Blue recorded a staggering 56.9 percent sales increase in that segment on Black Friday, along with a 43.2 percent rise in demand for home goods and 22.9 percent more activity at department stores. Now more than ever, it’s clear that businesses st learn to adapt for the fast-evolving shopping habits of consumers or risk falling behind as mobility continues to permeate online shopping.