Dynamic spectrum management is a promising solution for network operators to efficiently utilise the limited radio spectrum and guarantee operator's profit by increasing capacity as well as generating more spectrum opportunities for opportunistic use. This paper presents a novel algorithm for efficient spectrum management to optimise spectrum utilisation between two sharing UMTS cellular operators. It is shown that proposed solution approach increases revenue of sharing operators without sacrificing the quality of service on either network. A multioperator UMTS simulation tool is also developed to evaluate the performance of proposed algorithm. The simulation results show that the proposed algorithm achieves high efficiency of spectrum utilisation and gains up to 33% can be achieved for both uniform and non-uniform distribution of traffic.