Amazon.com Inc.’s toy prices were lower than those available online from Wal-Mart Stores Inc. and Target Corp. last week as retailers seek to attract shoppers heading into the crucial holiday selling season.

Amazon’s prices, excluding those from its third-party sellers, were 3 percent lower on average than Wal-Mart’s on a basket of 87 toys, according to a study conducted by Bloomberg Industries on Nov. 14.

Including the Marketplace vendors, which use Amazon’s platform to sell their own products, the pool of comparable goods expanded to 115, and Wal-Mart was cheaper by 1.2 percent, on average.

The pricing battle may help determine which retailers win consumers’ toy purchases during the holiday season. Sales in November and December account for 20 percent to 40 percent of U.S. retailers’ annual revenue, according to the National Retail Federation.

“Being competitive on toy prices is crucial to drive market-share gains during the holiday season,” Poonam Goyal, a Bloomberg Industries analyst in Princeton, New Jersey, said in a telephone interview.

Wal-Mart’s prices were 2.4 percent lower than at Target, 5 percent less than Sears Holdings Corp.’s Kmart and 7.2 percent lower than Toys “R” Us Inc., according to the study.

Bentonville, Arkansas-based Wal-Mart rose 0.1 percent to $79.30 at 10:19 a.m. in New York, while Minneapolis-based Target gained 0.2 percent to $66.60. Seattle-based Amazon added 0.2 percent to $369.84.