J. P. Morgan originally estimated its exposure to Enron at $900 million, in part because it had counted on recovering on the bonds. But the insurers have balked at paying, and J. P. Morgan is suing them. After reassessing all of its potential losses in the Enron debacle, J. P. Morgan said last month that its total exposure to Enron was actually about $2.6 billion. That amount included $965 million on the bonds and $165 million in a letter of credit, as well as loans secured by a natural-gas pipeline and unsecured loans. Both Citigroup and J. P. Morgan had also served as investment bankers to Enron. The two firms were advisers to Enron on the proposed sale to Dynegy that might have saved Enron from collapse. Together, they stood to collect advisory fees of about $90 million if Dynegy went through with that acquisition. Citigroup's Salomon Smith Barney investment banking unit also underwrote securities for Enron and the various limited partnerships the company controlled.