The SEC cannot announce that it’s working on a suspension. We conduct this work confidentially to maintain the effectiveness of any related investigation we may be conducting. Confidentiality also protects a company and its shareholders if the SEC ultimately decides not to issue a trading suspension. The SEC is mindful of the seriousness of suspensions, and carefully considers whether it is in the public interest and for the protection of investors to order a trading suspension.

http://www.sec.gov/investor/alerts/tradingsuspensions.pdf