"To continue operating, it drew on a line of credit from six banks amounting to between $500 million and $600 million to meet higher margin, or lending, requirements from its central clearing facility for stock trades, known as the Depository Trust & Clearing Corporation."
Non-zero chance had they not haulted trading on those symbols they would've been insolvent by close of trading today, depending on the size of their credit line.
I watched the CEO on CNN tonight, and while I found him pretty difficult to watch, this is a very difficult position to be in. If you admit on TV that your company is experiencing liquidity issues -- even if temporary in nature such as with clearing custodianship requirements -- you run the risk of triggering a greater panic through customer withdrawals/redemptions.
This could turn into a run on the brokerage pretty quickly, and probably already has in some measure, especially after a day of massively lost customer trust. He certainly didn't help it by going on TV and lying about their liquidity issues. They probably would've been better off by issuing a statement and keeping him off TV.