U.S. regulators announced Tuesday that embattled auto parts supplier Takata Corp. has acknowledged defective air bags in 33.8 million vehicles in what an official described as "the most complex" recall in the country's history.

The course of events hit Takata shares hard during trading on the Tokyo Stock Exchange on Wednesday, driving them down 10.21 percent to ¥1,353.

"This recall involves 11 auto manufacturers, many different parts suppliers, not just Takata, and roughly double the number of vehicles built in the United States every year," Department of Transportation Secretary Anthony Foxx said at a news conference announcing the move.