U.S. Senator Amy Klobuchar, D-Minn., on Friday called into question the FTC's decision to approve Amazon.com's (AMZN - Get Report) acquisition of Whole Foods Market (WFM) .

"As a ranking member of the Antitrust Subcommittee, I am concerned about the Federal Trade Commission's decision to not fully review Amazon's acquisition of Whole Foods," she wrote. "Amazon's increased access to data on consumers and their behavior, and its dominance in Internet retail sales, raises questions about whether this merger harms consumers and suppresses competition."

Klobuchar concluded by calling on the FTC to explain why it approved the deal as quickly as it did.

Shares of Amazon.com were lower in late morning trading on Friday.

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