The names and physical addresses of 65 million customers and email addresses of 13 million customers were among the assets listed as part of the sale, which concluded this week but has yet to be approved by a bankruptcy court.
RadioShack's March 2015 privacy policy promised: "We will not sell or rent your personally identifiable information to anyone at any time."
"When a company collects private customer data on the condition that it will not be resold, it is the companys responsibility to uphold their end of the bargain," said Attorney General Eric Schneiderman in a statement.
"My office will continue to monitor RadioShacks bankruptcy sale and whether it includes auctioning off private customer data. We are committed to taking appropriate action to protect New York consumers," he said.
The bankruptcy auction was won on Monday by Standard General LP, according to a report by Bloomberg. The hedge fund was RadioShack's largest shareholder and won with a bid valued at $145 million, the report said.
Approval of the deal could come on Thursday, when the bankruptcy court in Delaware is scheduled to rule on the sale.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com