The biggest U.S. banks will be required to limit their financial ties to one another under new proposed rules aimed at preventing the collapse of one big institution from triggering a larger, cascading crisis.

The net credit exposures between any two of the nation's six largest financial firms, including J.P. Morgan Chase & Co. and Goldman Sachs Group Inc., would be limited to 10% of a company's regulatory capital, under a proposed package of regulations released by the Federal Reserve on Tuesday. Most other firms covered...