Assertions of a "surplus" capital position are a perennial for Macquarie Group, and were dished out once more yesterday in the course of rationalising its purchase of a hefty Esanda portfolio from ANZ.Macquarie put this surplus at a minimum of A$2.4 billion as at June 2015, and maybe as much as $3.8 billion.If this is the case, why must the group set out to sell at least $400 million in new shares to meet the capital requirement to buy these loans from ANZ?"We like to have a level of surplus capital … with a normal level of organic growth, we probably generate enough capital through the business, but we like to raise capital" for an acquisition, explained Nicholas Moore, the Macquarie managing director, in a conference call yesterday."We need to raise capital to support a transaction of this nature."The group's notional capital surplus is simple arithmetic based on actual capital resources and regulatory minima.What is not disclosed is the actual minimum set by APRA (and which banks are not supposed to reveal) and the targets to which the board and ratings agencies really work.