Walmart.com, No. 4 in the Internet Retailer Top 500 Guide is planning discounts of up to 60% off for online shoppers on Dec. 10. The sales fall on an emerging online shopping holiday known as Green Monday, the second Monday in December. It hopes to echo some of its Cyber Monday success, by making Green Monday this month’s biggest for online shopping, it says.

“Given this highly competitive season, we are living up to our commitment with even more big savings online before Christmas that keeps more money in [shoppers’] pockets this year,” says Joel Anderson, president and CEO of Walmart.com U.S.

Cyber Monday this year was Walmart.com’s best day in history, the retailer says, and last year Green Monday was its highest traffic day in December.

After Cyber Monday, Black Friday and then Thanksgiving were the biggest days thus far this season for paid search for clients of digital marketing technology provider Kenshoo. Of all three days, Cyber Monday generated the largest year-over-year increases in search marketing impressions (66%), clicks (57%) and ad spending (51%), Kenshoo says. However, Thanksgiving took the top spot for highest average order value, at $150, up 19% year over year, the report says. Kenshoo says it expects Thanksgiving to overtake Black Friday next year, becoming the second largest online shopping day.

Meanwhile, marketing technology company Monetate reports that its clients generated more than $1 billion in online sales over the Thanksgiving shopping week, up 44% year over year. Monetate’s clients include Best Buy Co., No. 11 in the Top 500 Guide; Macy’s Inc., No. 14; Aeropostale Inc., No. 114; The Sports Authority Inc., No. 230 and PETCO Animal Supplies Inc., No. 231.