Cruise operating giant Carnival is to enter into a closed period share repurchase programme, the firm announced on Thursday.In an extremely short statement with limited details, Carnival revealed that it has entered into an "irrevocable, non-discretionary programme to puchase ordinary shares of Carnival plc".The programme will take place between 1 September and 30 September, unless it is terminated earlier."Any purchases under the programme will be effected within certain pre-set parameters, the Listing Rules, other applicable laws and in accordance with Carnival plc's general authority granted by its shareholders at the last annual general meeting to repurchase shares."BC