Commonwealth Bank will sell $700 million in hybrid securities, CBA said yesterday. The securities will be "non-innovative" and count as tier one capital.They will be structured as preference shares along the line of the prior "PERLS" hybrid sold by the bank.Apart from providing room to manage market-leading lending growth, and any small-scale acquisitions the bank may have in mind, CBA may also want to bolster core capital to meet the florid expectations of sections of the market.As in the case of the Bendigo and Adelaide Bank profit reported on Monday, the sell-side analyst set seems to be producing estimates of bank capital ratios, and especially core capital, which are higher than those ultimately reported by banks.The reason appears to be that banks are reporting higher levels of risk-weighted assets than predicted by the analysts' models, itself an interesting indicator of the difficulty that outsiders face in modelling the financial affairs of banks operating under the present-day regulatory blanket.