Holiday e-retail growth finished at about 13% year over year, with online sales coming in at about $69 billion, according to comScore Inc., the web measurement firm that will release its full 2015 holiday figures Friday.

The numbers fell a bit short of comScore’s prediction of $70 billion sales and 14% growth. Sales from personal computers only grew 6%, less than the 9% growth comScore anticipated, but mobile growth of 60% over the holiday season partly made up for the shortfall, comScore says.

Holiday online sales for ChannelAdvisor Corp. retail clients increased 13.3% year over year for the period Nov. 1 to Dec. 31. Sales by those retailers on the Amazon.com marketplace grew 16.8%, while sales for merchants on eBay.com lagged at 4.8% growth, according to ChannelAdvisor, whose online marketing services include facilitating retailer clients’ sales on web shopping portals like Amazon, eBay and 50 others in the United States and abroad.

For retailers selling on marketplaces excluding Amazon and eBay, sales for the holiday season surged 48.7% compared with 2014. Google Shopping, mainly sales from clicks on Product Listing Ads on Google search results pages, increased 31.7%, ChannelAdvisor says.

ChannelAdvisor also reported the following results for its retailer clients:

• Cyber Monday, the Monday after Thanksgiving, was by far the peak day, followed by Black Friday and Green Monday (Dec. 14).
• Cyber Saturday (Nov. 28) was the peak day for visits from smartphones to retail sites, as phones accounted for 53% of online traffic. Counting tablets in mobile statistics for Cyber Saturday makes it the peak mobile day with 68% of traffic compared with desktops at 32%. Mobile traffic could push into the high 70% range during the 2016 holiday season, ChannelAdvisor says. “If you are a retailer that doesn’t have a mobile-first strategy, 2016 has to be the year,” chairman Scot Wingo writes in the holiday report.

• Cyber Monday ranked as the lowest mobile day, with mobile at 55% of traffic and desktops accounting for 45%.

E-commerce technology provider MarketLive Inc., meanwhile, reports online revenue driven by smartphones shot up 50.2% for its e-retailer clients during the holiday season, defined as Nov. 23-Jan. 3, when compared to the same period a year ago. Traffic from smartphones increased 18.6% year over year. The conversion rate on smartphones increased to 1.3% from 1.2% in 2014, an 8.3% increase, while average order value hit $140.63 in 2015 compared with $129.06 in 2014, a 9.0% increase.

Overall, year-over-year online sales increased 8% while traffic rose 21% from Nov. 23-Jan.3, MarketLive says. The conversion rate declined to 2.7% from 3.1%, a 12.9% drop. Average order value rose to $147.24 from $139.24, up 5.8%, the report says.

And for all the online buying, there’s plenty of returning.

Most consumers (64%) prefer to return or exchange gifts in stores, while only 12% prefer to do so online and 24% had no preferred venue, according to a report by Retale, which provides retailer circulars to consumers via a mobile app. Retale polled more than 500 U.S. consumers.

Results from this year’s poll were slightly more favorable for online returns compared with last year’s survey, which found 70% of consumers preferred in-store versus 9% online and 21% had no preference, according to Retale.

The 2015 poll also finds that 54% of consumers called online returns and exchanges convenient while 75% of respondents said the same of in-store returns and exchanges.

“While retailers advocate this multichannel experience, they are fast coming to understand that processing returns in-store, for purchases made online and with free shipping, comes with an additional cost,” says Retale president Pat Dermody.  “Whether they will ultimately be able to absorb the impact and continue to offer this convenience to multi-channel shoppers, without charging them, remains to be seen.”