過去文獻顯示，學術界對於顧客集中程度的高低存在正反兩極的評論，本研究透過兩種方法定義顧客集中(Concentration)，設定1989年至2013年美國上市公司為研究對象，探討顧客集中程度與銀行借款利率的關聯性，以多元迴歸分析方法進行實證。另外，以額外測試檢視顧客集中和借款到期期間之關聯，進一步探討顧客集中對公司舉債條件是否也造成影響。實證結果顯示，顧客集中和銀行借款利差呈現顯著正相關，表示顧客集中程度越高，會為公司帶來較高的銀行舉債成本，也證實顧客集中確實連帶影響公司舉債成本。

SUMMARY
Prior studies determine whether the level of the customer concentration is positive or not. In these studies, we define customer-base concentration through two methods, using samples from 1989 to 2013 listed companies in the U.S., investigating the relationship between customer-base concentration and loan interest spread to conduct empirical regression analysis. Further, we take an additional test to conduct the relationship between customer-base concentration and loan maturity, and explore how the customer-base concentration determines the loan contract terms. The empirical results show that the customer-base concentration is significantly positive to bank loan spreads. And therefore due to the higher level of customer-base concentration, the company will lead to higher borrowing costs, also confirming that the customer-base concentration really affects the company's borrowing costs.

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