These are "sobering times" in the banking sector, David Carter, chief executive officer, banking and wealth at Suncorp says."I suspect that credit growth is slowing," Carter told Banking Day last week."The S&P piece [the downgrade of credit ratings for many banks] has made people relook at all that data," he said, a reference to the level of debt to income ratios and the unyielding growth in the level of property prices, especially in Melbourne and Sydney." Suncorp Bank retained its A+ rating when S&P last month sliced by one notch the rating of many peers and smaller ADIs.APRA's widening of macroprudential measures in late March, with a focus on limiting the supply of interest only loans, is leaving an impact, at least as viewed by Suncorp.The bank on Friday opted for a rare, near across the board lift in interest rate on its mortgages.Variable interest rates on all new and existing investor home loans, will increase by 0.12 percentage points from early July, Suncorp announced on Friday.In contrast, ANZ on Friday said it would cut variable interest rates by five basis points, taking the bank's standard variable rate for owner-occupiers to 5.20 per cent."Judging from the behaviour you've seen from everyone in the market; the willingness to change or stop [lending products] at little or no notice suggests APRA has been very effective," Carter said.Carter said with the flurry of product changes this year, including of investor lending "it's almost impossible to understand what really is the underlying demand."As a small bank we may not be taken as true indicator of the market and investor lending. Among owner occupied people are still buying houses and refinancing, but I suspect that credit growth is slowing."APRA have been very engaged, especially over the last eight months on responsible lending."Speaking at Suncorp's investor day two weeks ago, Carter said that APRA's efforts "impacted our growth in the first part of this year. We are relatively more conservative and we became relatively more difficult to deal with."He explained then that Suncorp's "interest-only portfolio runs at about 25 per cent versus the cap of 30 per cent; our investor portfolio of growth the way APRA measures it is growing at seven per cent, below the APRA cap of ten per cent, and depending on how you measure it, 80 per cent of our customers are at least one month ahead of their repayments, 70 per cent are three months ahead."