Wish I could help, but as of 03/28/2014, this is all TD Ameritrade could tell me:
Hello Jason,
I checked and verified that NNAB is still listed as an active security. It's possible that it will start trading again in the future. Unfortunately, we don't have any information about when or if that will happen.
Please reply to this email if you have any questions.
Thank you,
Clinton Pearcy
Apex Client Services, TD Ameritrade
TD Ameritrade, Inc.