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It's my understanding that the "moneygrubbing Jew" stereotype came about from the Middle Ages, when Christians were forbidden to loan money at interest. Jews were uniquely placed to become moneylenders, as they had no specific religious laws against it, and thus the stereotype of Jewish bankers came to pass. (There's a lot more to it than that-- Jews were often not allowed other kinds of work, their positions gave them power but also made them targets when times got tough, etc.)
I'm sure someone here has a better background on the history, but I'm almost done with coffee break, so hopefully that at least helps.