Only a handful hot topics animated yesterday's three hour appearance by CBA chief executive officer Ian Narev before the House of Representatives' Standing Committee on Economics in Canberra. The first turned on inflows into CBA's priority term deposit products. These had exceeded the bank's projections of A$1 billion a week by 50 per cent.Narev explained that inflows of $1.5 billion a week warranted removal of rates that had proved too attractive for investors. At the time these rates were introduced, they were featured by CBA as a PR counterpoint to what was viewed as a lame cut in home loan rates in August.A genuine rumble centred on the resistance of Narev to detailing the return on equity on mortgages and credit cards, data requested by Labor MP Pat Conroy.Asked to elaborate on the bank's return on equity on housing loans, Narev pointed out that: "We don't disclose" that, leaving industry analysts to model sky high returns.He pointed out that CommBank holds $5 billion more capital on mortgages now than a year ago - mainly a function of APRA policies.Narev also did not indulge the committee with the level of returns on credit cards, calling it information that "our competitors would love to have."The CBA CEO did concur that returns should "represent the return the people that provide the capital [expect] ... above the cost of capital".Narev also weaved in the bank's stance on portability of bank accounts.Commonwealth Bank would work "very constructively" to foster any mandated project to allow portability of bank account numbers, he confirmed.Pressed by the committee to put the bank's view on revitalising a reform considered and deferred more than once over the last decade, Narev showed little enthusiasm.He said the bank put the "safety and … security" of customer transaction data as its priority.Yet CBA would engage with a portability project as it has with the New Payments Platform, Narev said.