From the Securities Investor Protection Corporation website, http://www.sipc.org/pdf/HSPY_English_2011.pdf :
“Terms of SIPC help. Customers of a failed brokerage firm get back all securities (such as stocks and bonds) that already are registered in their name or are in the process of being registered.”
Securities registered in the “Street Name” of the brokerage do not appeared to be covered. Beware! Do not delay or fail to insure your stocks are placed in your name. If a large scale financial event were to happen, the reserve funds of the SIPC could be depleted and you would be at risk of notable losses.