Amazon is using one of its biggest assets in an aggressive push ahead of the holiday season

Reuters/Edgar Su

Amazon is getting more aggressive online.

• Amazon sells millions of products on its website, but it also has a robust third-party-seller platform.
• Amazon has now started to offer discounts to customers purchasing select third-party items - and the retailer is picking up the difference.
• This is an especially aggressive push by the retailer, and it leverages one of Amazon's unique assets.

Amazon has just instituted a new program that affects both sellers and their customers - and both stand to win substantially from the deal.

Amazon has started discounting a number of third-party-sold items, passing the savings on to the buyer but covering the amount of the discount, according to a new report by the Wall Street Journal.

It's another example of what Amazon is willing to do to gain market share at the expense of its own profits. It'll make Amazon even more of the one-stop shop it already aspires to be. The move comes as big-box retailers known for their low-cost, like Walmart and Target, move more aggressively online.

It's currently unclear how Amazon chooses which items it will cover discounts for, which can be as much as 9%, according to reports. All the items currently discounted are enrolled in the Fulfillment by Amazon program, which involves third parties sending the items to Amazon fulfillment centers to be stored and shipped like the retailer's regular products.

Amazon told the WSJ that sellers can opt out of the program.

The move could also increase the perception of Amazon as the "everything store," where convenience and selection are both paramount in the eyes of consumers. Part of Amazon's appeal is that it sells so many different items through its third-party sellers program, which is growing to be just as large as the rest of its retail business.