In 1968 the Pennsylvania Railroad and the New York Central Railroad merged to form the PennCentral Railroad. Two years later, PennCentral unexpectedly filed what was then the largest corporate bankruptcy case in American history. PennCentral had financed its operations with more than $70 million in money market paper, and the default had the effect of dislocating the money markets in the United States for several weeks. Investors lost confidence in other corporate issuers and stopped refinancing maturing commercial paper. Within three weeks of PennCentral's bankruptcy, the amount of corporate commercial paper outstanding had dropped almost 10 percent. As a result, most large corporations began to keep lines of credit with large banks as a "backup" in case such an event happened again. Does the case above suggest the limitations to that strategy