研究調查發現，至少45%公開發行公司，依賴一個主要顧客為其帶來可觀營收，可見得顧客集中儼然已成為企業與企業間交易的常態，無論是投資人或債權人均應瞭解其所帶來的影響。過去文獻指出顧客集中可能為公司帶來經營效率，並為公司帶來鉅額可觀之營收，但也可能因主要顧客財務狀況不佳、更換供應商等原因，決定抽單，公司未來營收受到影響。本研究主要探討顧客集中與公司債籌資成本及信用評等之關聯性，結果發現當顧客集中度高時，信用評等較低、公司債利差較高。本研究另採主要顧客銷售額占總公司銷售額之比例為替代變數，進行額外測試後，也發現類似結果。整體而言，顧客集中造成公司資金成本提高，進而降低公司價值。

The study investigates the relation between customer-base concentration and bond yield spread. We find firms with higher customer-base concentration exhibits lower credit ratings and higher debt costs. Further, we employ major customers’ sales to firms’ sales as our additional tests to robust our main tests. We find similar results. Overall, our findings suggest that customer-base concentration significantly impact firms’ cost of debt that could impair firms’ value.

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