Shares of Covanta (CVA) - Get Report have dropped 25% in the past year, but have jumped 33% since their mid-February low. The company's CEO Stephen Jones said investors have historically been confused by the waste-to-energy supplier's business model, but are coming around. 'Two thirds of our revenue comes from the waste side of our business, so I think that has started to become clearer to investors as time goes on,' said Jones. 'But historically we have traded more like an energy company and that is starting to switch over.' Moody's changed the company's credit outlook last week to negative from stable while affirming Covanta's debt rating at Ba2.