In newly released answers to a House panel investigating four Big Tech firms, Amazon maintained it does not use data from individual third-party sellers to come up with its own products. But it does use "aggregated data" to inform its private label brands, the company said.

Amazon's use of private data to shape and promote its own branded goods seems to be a key question for lawmakers and regulators probing the company's competitive practices. If investigators believe Amazon holds a dominant marketplace position, they could seek evidence that would point to the company using its dominance to compete against third-party sellers that also rely on Amazon's platform for their livelihood. Bloomberg reported in September that the Federal Trade Commission has been interviewing sellers on Amazon's marketplace over antitrust concerns.

Private label products are created by Amazon or partners and are sold only on Amazon's website under an exclusive brand name. They benefit Amazon in many ways: They expand the selection of products on the site, offer better profit margins than selling third-party products, make supply-chain management easier and can help Amazon persuade big brands to cut prices to remain competitive on its site.

Amazon has been ramping up the number of private label brands it sells during the last three years, stoking fear and concern among some sellers and brands that sell competing products on the marketplace. The company says it now offers roughly 158,000 private brand products, plus additional variations on those products.

"Just like other stores, Amazon uses public and aggregated data from its stores to identify categories and products with high customer demand over a given time period," Amazon wrote in its response, defining aggregated data as "data that is aggregated across all third party sellers and Amazon's first-party sales and is therefore not specific to an individual seller. It includes data such as aggregate sales reports at a product category level."

The company also said it offers "free, anonymized shopping behavior analytics reports" that sellers can use to help figure out what other products customers looked at and what they searched for.

An Amazon spokesperson declined to comment.