Share your insights or perspective on the financial matter presented in the input.

Fractional Reserve Banking and Insolvency
A bank is insolvent when it can no longer meet its short-term obligations.  In this example, the bank is insolvent when depositors withdraw more cash than the bank can pay out. In this case, it's probably something in the range of $600-700k, because the bank can borrow money from other banks using assets as collateral. In the US, we manage this risk in a few ways. First, FDIC insurance provides a level of assurance that in a worst-case scenario, most depositors will have access to their money guaranteed by the government. This prevents bank panics and reduces the demand for cash. The risk that remains is the risk that you brought up in your scenario -- bad debt or investments that are valued inappropriately. We mitigate this risk by giving the Federal Reserve and in some instances the US Treasure the ability to provide nearly unlimited capital to get over short/mid-term issues brought on by the market. In cases of long-term, structural issues with the bank balance sheets, regulators like the FDIC, Federal Reserve and others have the ability to assume control of the bank and sell off its assets to other, stronger institutions. The current financial regime has its genesis in the bank panics of the 1890's, when the shift from an agricultural based economy (where no capital is available until the crops come in!) to an industrial economy revealed the weakness of the unregulated model where ad hoc groups of banks backed each other up. Good banks were being destroyed by panics until a trusted third party (JP Morgan) stepped in, committed capital and make personal guarantees.