"The composition of housing and mortgage markets is becoming unbalanced," the Reserve Bank of Australia declared in its half-yearly Financial Stability Review."Some institutions appear to be lending at high loan-to-income ratios and, overall, the average size of new loans has risen recently," it said, without divulging which institutions it considers the worst offenders. More broadly, the RBA said "banks' lending standards have been holding fairly steady overall; while some elements or market segments have eased a little, others have tightened up a bit."Loans at valuation ratios of more than 90 per cent have "trended down" since early 2013, it said."Only a small share of new lending currently appears to have both a high LVR and a high loan-to-income ratio, which implies that few households are simultaneously exposed to the risks of falling into negative equity and facing difficulty making their loan repayments," the RBA said."Any increase from the current small share of new lending with both a high LVR and high loan-to-income ratio would, however, be undesirable and this configuration of lending continues to be closely monitored."The RBA said banks' "aggregate interest-only share of new lending" needs close monitoring and "might be indicative of speculative demand motivating a rising share of housing purchases."