Rumors of the death of Cyber Monday have been greatly exaggerated, or at least floated prematurely. The Monday after Thanksgiving appears to be retaining its crown as the biggest e-commerce shopping day of the year, despite the overwhelming shift from PCs to mobile phones and tablets.

Increasingly, there is little reason for this to be. The term Cyber Monday -- first coined in 2005 -- refers to the first day back at work after the Thanksgiving holiday, a day when workers returned to work and used their desktop PCs and broadband connections to get a jump on holiday shopping. That day seems like a lifetime -- and several generations of smartphones -- ago.

Today more than half of all traffic to retail websites is from mobile devices and nearly a quarter of all online purchases are conducted via a tablet or smartphone, according to data from IBM. As mobile devices and broadband connections proliferate, Thanksgiving itself has emerged as a huge day for online shopping, not to mention Black Friday and the weekend following.

Still, consumers are still doing plenty of shopping when they go back to work. As of 10 a.m. on the East Coast, Cyber Monday sales were up 17 percent from last year, driven by upticks at big-box retailers (up 20 percent) and, of course, mobile devices, according to Adobe. At midday, IBM had sales up 9.2 percent, nearly as much as the faster-growing Black Friday (9.5 percent).

This year purchases shifted to earlier in the day as shoppers responded to promotional emails sent by retailers overnight. Adobe retail analyst Tamara Gaffney says sales appear to be peaking much earlier in the day than in past years as people use their mobile devices for more purchases.

"It means people are using their phones at work and when they're in transit," Gaffney said. "People are starting their shopping before they've even left the house."

Big retailers with a data advantage over smaller ones are using that to tailor deals to different consumers. "We are seeing bigger retailers capturing all this growth; the bricks-and-clicks did better because they can fulfill in-store when customers buy online."

As has been the case for several years now, the big story is the shift from PCs to mobile devices. Mobile traffic accounted for 39.9 percent of visits to retail sites on Cyber Monday and accounted for 23 percent of sales, according to early data from IBM.

“I think we’re seeing a transition in how most people do their holiday shopping,” said Jay Henderson, director, Smarter Commerce, which tracked 800 U.S. retail sites. “The other trend is that the shopping period isn't as concentrated, which is turning Cyber Monday into Cyber Week."  

The shift to mobile has only just begun. Consider: Apple iOS users continue to dominate mobile commerce in the U.S. where it has 41.9 percent of the smartphone market, according to comScore. Logic would dictate that Android users will become more of a force going forward.

But as online and mobile shopping become the mainstream, it’s a reminder that it’s all just shopping and except perhaps for Apple and Samsung, mobile devices aren’t changing fundamental economics. A National Retail Federation survey predicted overall sales would be down 11 percent over the Thanksgiving weekend, a sign of continued caution among consumers. That caution also showed up in the online numbers, where average orders were $135.51, flat compared to 2013, according to IBM.

If trends hold, Cyber Monday should ring in the expected $2.6 billion in sales, a shade over Black Friday’s $2.4 billion. Nine years later, Cyber Monday is still alive and still well, but next year, on its 10th birthday, it will be overtaken by Black Friday in sales and subsumed into another day in the retail dogfight that starts before the turkey even hits the table.

"It's not like it's going to go away," Gaffney said. "But it is going to become less critical."