This is the not the first time the Romney campaign - or the candidate himself - has highlighted Steel Dynamics as a shining achievement of his time at Bain Capital. In fact, Romney often mentions the manufacturer in the same sentence as his other success stories, which include the office supply giant Staples and the sports equipment store The Sports Authority. The company was also featured in a television ad the campaign distributed during the days leading up to the South Carolina primary.

And just last month at a campaign event in Westerville, Ohio, Romney spoke at length about Steel Dynamics, recalling the day when a "an entrepreneur came to us and said, 'I want to build a steel mill.'"

Initially wary of the chances of success for a steel company U.S., Romney said he was convinced.

"We said 'where?' - certainly not the United States because steel mills are closing left and right, we've been an investor in a steel company that didn't make it," Romney said. "We looked at the numbers, looked at the data, looked at the facts, sure enough we invested and we started this steel mill which became very successful and is called Steel Dynamics Incorporated, located in Indiana today."