Many investment banks, such as Bear Stearns and Lehman Brothers, have relied too much on cash from short-term deposits to fund their long-term investments. If too many lenders claimed their debt at the same time, it was like an old-fashioned race to the bank. There are mechanisms built into the buyback space to reduce this risk. For example, a lot of rest is over-guaranteed. In many cases, if the collateral loses value, a margin call may take effect to ask the borrower to change the securities offered. In situations where it seems likely that the value of the security may increase and the creditor may not resell it to the borrower, the subsecure may be used to mitigate the risks.