You didn't mention whether it was a cash account or a margin account, or if there's an exception for fully paid securities. If it's a margin account, that is indeed how it works for non-fully paid securities. If it's a cash account, or there's no exception for fully paid securities, regulators will probably not view that agreement favorably. You can file a complaint at https://www.sec.gov/complaint/tipscomplaint.shtml. In my experience, they actually read and act on complaints. (Well, at least small easy to investigate ones... ones requiring a lot of investigatory work like the Madoff case are a different story.) The relevant regulation is 17 CFR ยง240.15c3-3, paragraphs b(1), b(3), and b(3)ii. (http://www.ecfr.gov/cgi-bin/text-idx?SID=f07570958d348a3f75d...)
