Delivering quality customer service has emerged as a strategic imperative for retaining profitable corporate customers. Sharing valuable information is one of service that could effective to enable seller-buyer relationship formation, maintenance and long-term continuation. This paper presents an empirical study that attempts to understand the impact of information sharing service on the corporate customer's attitude towards loyalty. Moreover, this study investigates the effects of different degrees of information sharing services on customer groups classified by trading value and trading frequency. Data from 239 corporate customers of a large steel supplier in Taiwan support hypotheses that information sharing services positively influences corporate customer's attitude towards loyalty and the types of customer groups moderate the effect of information sharing service. The findings of this study suggest that although providing information sharing services is the important means for enhancing customer loyalty, not all types of customer should be treated equal. The customer group, classified by low trading frequency and low trading value, may not perceive value for the information service provided by the seller. The seller may not need to invest information technology resources for providing information sharing service to such customer group.