LONDON (Reuters) – The European Union’s securities watchdog said on Thursday it had ordered top rating agencies to take action to ensure that their ratings of collateralised loan obligations (CLOs) are accurate and independent, after an investigation raised some concerns. The European Securities and Markets Authority (ESMA) said its investigation focused on Fitch Ratings, Moody’s and S&P – often referred to as the “Big Three” – given that they account for the vast majority of CLO ratings. CLOs are securities backed by a pool of loans, often linked to companies with lower credit ratings. “ESMA …