Historically in Europe, the majority of Jews, or at least the Jewish stereotype in the public eye at the time, were proponents of capitalism. The general perception of the group was of bankers or other somewhat high-class citizens, often with control of the monetary system or benefiting from a capitalistic economy. Capitalism created economic disparities between groups, and many were discontent with the system as an economic structure. Jews were seen as representatives of the capitalistic economy, so people unfairly blamed the problems in society, created by capitalism, on them. Anti-Capitalist sentiments became antisemitic because Jews were seen as representative of capitalism, and subsequently blamed for its problems within the economy.
Although some people might think this way, it is more of a historical perspective. Most anti-Semites don't use capitalism as justification, and society has progressed past this stereotype still being relevant.
[P1] Jews were seen as representative of capitalism. [P2] People had criticisms of capitalism due to its negative impact on the economy and working class. [P3] Criticisms of capitalism became criticisms of Jews due to their supposed contributing role.