Abstract: Data processing for an improved securities brokerage-cash management system supervises, implements and coordinates a margin securities brokerage account; participation in one or more short term investments; and subscriber unilaterally initiated use of charge, debit or checking instruments. Subscriber expenditures, effected as by charge card use, check and/or cash advance are applied on a hierarchal basis, seriatim, against the subscriber's free credit balance, short term investment and the lendable equity in his securities account. On a periodic basis, e.g., daily, received card charges, check, securities and deposit transactions for the ensemble of account participants are verified and employed to compute an updated credit limit for each subscriber.In accordance with one aspect of the present invention, the short term investments available to subscribers include an ordered ensemble of insured savings accounts.