Citigroup is underwriting a collateralized debt obligation worth $500 million, sources said. The CLO, which comprises high-yield and high-risk loans, is expected to price this week. It would be the first CLO offering in more than a year. "This is the first baby step to getting the market going again," said Matt Natcharian, head of Babson Capital Management's structured-credit team. "There is a decent amount of investor interest throughout the capital structure, and there are managers that want to do deals."