Mumbai: Global credit rating agency Crisil has placed IndusInd Bank's long-term debt instruments on 'Rating Watch with Negative Implications.' This includes Rs4,000 crore worth of tier II bonds and Rs1,500 crore of infrastructure bonds. The move comes after a series of recent developments at the bank that have raised concerns about its internal controls and management stability. According to Crisil, the rating action follows the resignation of two senior executives at the bank, along with the bank's disclosure that its internal audit department is reviewing the microfinance business. This review was prompted by certain concerns that came up during the finalisation of the bank's accounts. Earlier in March, the bank had also revealed an issue with how it had accounted for some derivatives, which further deepened the worries.