When, in stressed conditions, the credibility of the promise came into question, the susceptibility to runs increased dramatically. In some cases, there were explicit contractual provisions for liquidity support or credit enhancements, such as were provided to ABCP vehicles by their sponsoring banks.
In other cases, the support was more implicit, and was conveyed in the marketing of the assets or through an historical pattern of providing support. Forms of implicit credit support were present in a variety of important funding channels and, to a considerable degree, persist today. Three examples are money market funds, the triparty repo market, and securities lending.