Molycorp (NYSE: MCP) revealed today that it is under investigation by the SEC. The news, which sent shares down by as much as 13%, came the day after the rare-earths miner reported a $0.19-per-share net loss for the third quarter of 2012. That loss, reported after the market closed Thursday, was smaller than expected and Molycorp's shares had opened higher when trading resumed Friday.

However, in its 10-Q quarterly report filed today with the SEC, Molycorp revealed a bit of information that had gone unmentioned in its earnings release yesterday. On page 30 of the 61-page filing, the Colorado company stated that: "In August 2012, the staff of the SEC notified the Company that a formal order of investigation had been issued regarding, among other things, the accuracy of the Company's public disclosures."

Molycorp said in the filing that it is cooperating with the SEC and cannot predict the "length, scope or results of the investigation or the impact, if any, of the investigation on the Company's results of operations." Shares dropped as much as 13% in response to the news, before recovering slightly.