Mumbai: Most private bank stocks declined after their second-quarter results disappointed investors.Kotak Mahindra Bank dived 4.7% and RBL Bank plunged 13.8%. HDFC Bank shares advanced 2.6%, emerging as sole gainer in Bank Nifty index, which shed 0.3%. Benchmark Nifty ended 0.3% lower at 24,781 in choppy trades.Analysts said the deterioration in asset quality, especially in the microfinance and credit card segments, and pressure on margins impacted profitability."Deterioration in asset quality is being driven by higher slippages, particularly in the credit card and microfinance segments," said Manish Chowdhury, head of research at Stoxbox.There is an issue of over-leveraging among younger borrowers, said Suresh Ganapathy, head-financial sector research at Macquarie Capital. "When the bank gave a loan at that time, there could be, say, two loans for the borrower...a few quarters later, the guy has taken three more loans thanks to NBFCs, Fintechs and other smaller banks," he said. "With inflation and other issues, he is facing difficulty in paying off the loans. The issue we are hearing is that on credit cards, many are withdrawing cash and then paying off their home loans or auto loans. That kind of behaviour is emerging at the junior level, Gen Zs and millennials - there is indeed an issue."A look at bank stocks that have seen outsised moves based on their earnings in Monday's trading:HDFC BankThe stock bucked the weak trend in the banking sector because investors are of the view that the lender is in a better position to deal with margin pressure."Although the bank has faced NIM (Net Interest Margin) pressure, a common issue within the banking industry, we believe there are strong indicators that the bank will improve overall profitability going ahead," said Chowdhury.HDFC Bank's shares rose 2.3% in the last five sessions against an up move of 0.1% in the Bank Nifty in the same period. "HDFC Bank has gone up as buying interest in the stock has come back as it is a defensive stock with stable asset quality," said Kaitav Shah, lead BFSI analyst at Anand Rathi Institutional Equities. "However, growth challenges remain as attested by the management as well and may persist until next year."RBL BankThe weakness in the stock was after RBL Bank's net profit dropped 24% from a year ago due to asset quality issues in its credit card and micro-lending portfolios."Investors should carefully consider the risks posed by these asset quality challenges before making any investment decisions," said Chowdhury.