Target, Wal-Mart Stores Best Buy and other chains are offering heavier discounts and a bigger online selection to help keep up with Amazon.com Inc. this holiday season.

Obviously, maintaining market share is worth squeezing margins.

As Black Friday ushers in the year-end shopping rush, chains are touting larger price cuts than in 2015, according to a Market Track study of holiday circulars. The study shows that Wal-Mart is offering an average discount of 39 percent, compared with 35 percent last year. At Target, the price cuts grew to 38 percent from 36 percent.

Wal-Mart and others also are steering customers toward online deals, rather than just physical stores. Black Friday marks the beginning of a streak of online promotions called "Cyber Week." Wal-Mart has tripled its e-commerce selection to 23 million products this year, aiming to better compete with Amazon. The world?s largest retailer said in a statement Friday that Thanksgiving was one of its top online-shopping days this year and that about 70 percent of the traffic to its website came from mobile devices.

Target is offering 15 percent off almost everything in its stores and website for two days: Sunday and Monday. The retailer said that Target.com saw double-digit growth on Thanksgiving, marking its biggest day ever, driven by deals on electronics. Televisions, Apple products and wearable gadgets were among the top sellers.

Best Buy is offering an average discount of 41 percent, compared with 34 percent last year. And Macy's avearge discount this year is 56 percent - six percent higher than last year's.

EBay started offering discounted phones the day before Thanksgiving, christening the event "Mobile Wednesday."

Market leader Amazon said on Friday that mobile orders on Thanksgiving topped last year's holiday and Cyber Monday combined. Black Friday is on pace to beat last year in terms of items orders. Top-selling items include Instant Pot cookers, Hasbro Inc.'s Pie Face game and Amazon's Alexa devices.