Abstract: This paper re-examines the compradors’ private trade within foreign companies in modern China throughthe lens of the comprador's role as a guarantor. Given the significant role of personal ties in modern Chinese commercialpractice, this paper argues that private trade embedded in local social networks was a crucial prerequisite for compradors toassume guarantee liability. The multitask principal- agent model constructed on this basis reveals that the autonomy olcompradors’ private trade increases with the proportion of idiosyncratic risk and decreases otherwvise; when idiosyncratic riskdominates, a positive correlation between risk and incentives may emerge. A case study of the Hongkong and ShanghaiBanking, Corporation provides appropriate empirical evidence for the theoretical analysis. Consequently, this paper no longeiviews private trade as a fundamental flaw of the comprador system, but rather as an endogenous choice made by foreign mer.chants to mitigate the credit risks associated with Chinese merchants.