IB is the 17th largest securities company. The top 16 got bailed out by the US government. IB had buy out offers from morgan stanley and goldman sachs but turned them down.
I believe that the 669 million figure for IBKR represents a 10% interest in the company. ie, Petterfly owns a 90% controlling stake, and the entire company is therefore "worth" 6.69 billion. However don't take my word for it - if you dig around the IBKR web site you can find a corporate tree that explains the structure in more detail.
my bad then. I trust Bloomberg too much. They usually add all the interests. Eg for petrochina, google etc. I split between ib and etrade, but worry about the sipc limits...
I believe the answer is yes but as this isn't my area so if you you're serious, send me a PM with amounts you're looking at and I'll see what I can find out. Mkt cap: as mentioned, only 10% of IBKR is floated and thus the true market cap is much higher relative to what is reported on many financial sites. Also, your comparison to other firms in regards to safety is missing a key point - DEBT. IBKR has very little debt and does not hold any CDO's, subprime debt or credit default swaps.