The $28MM decline in net capital probably reflects distributions of capital to repay credit line. The fact that the net capital requirement on a linked month basis was steady at $29MM is strongly suggestive that Penson is not losing customer accounts or balances (net cap requirement is equal to 2% of aggregate customer debit items, which, all other things being equal, would tend to fall dramatically if people were transferring accounts or balances, since the debit balances kind of have to follow the securities collateral).
Penson has an earnings problem, not a capital, near-term solvency or liquidity problem.
There is another side to the problem... an expenditure problem. It seems they are working on the expenditure problem by converting to Broadridge, dropping the Europe operation (which was losing money), RIF, etc. Hopefully 1st quarter will show some progress being made on the financials as these changes take hold.