This method groups multiple merchandises (products/services) and multiple traders (buyer/sellers/carriers) that share similar properties with a Merchandise Group ID (MGID) and a User Group ID (UGID), respectively. Each MGID and UGID represents one Merchandise Group and Trader Group, respectively. Different MGIDs and UGIDs represent different merchandise and trader groups. The method also utilize a multi-party matching mechanism to trade Merchandise Groups among Trader Groups by having grouped buyers/sellers/carriers place bid/ask/cAsk offers on both the merchandise and any shipping services required to fulfill the transaction. Based on offers received, the system calculates Gap Values in real-time to determine if deals can be closed. Like stock tickers, MGID enables grouped merchandise to be traded like stocks. UGID enables grouped traders to trade desired merchandise with acceptable counterparties through matching both MGIDs and UGIDs. Based on the grouping, matching and gap value calculating mechanism, this method changes "Instance Trading" into "Group Trading".