St. Jude Medical shares down 6 pct.

Shares of St. Jude Medical are down about 6 percent Wednesday following a disappointing earnings report and a heads-up from the company that federal health regulators may issue a warning letter about one of St. Jude's manufacturing facilities.

During a conference call with analysts, CEO Dan Starks said the Sylmar, California plant makes cardiac rhythm products. But he wouldn't specify what's drawing the FDA's attention.

"The right process here is to have FDA finish its inspection and go from there," Starks said. "When you say, 'What's wrong with Sylmar?' In the sense that you're asking it, nothing. There's nothing."

But Stark later said a warning latter should not be a big surprise, given concerns that have been raised about the company's Riata brand wires that connect medical devices to the heart. St. Jude stopped selling Riata and Riata ST wires in 2010 due to safety concerns. But thousands of people still have the wires implanted.

"I'm not particularly worried that this warning letter will lead to the ultimate smackdown, which would be shutting down production," said Debbie Wang, an analyst with Morningstar. "The company has a chance to address the issues that have come up and correct any issues that need to be corrected."

The news about the FDA came as the medical device maker posted net income of $176 million for the three months ending September 29. That was a 22 percent drop compared to the same period a year ago.