if required. In the financial industry The most common form of hypothecation is a repo transaction: the creditor gives a loan to the debtor and receives in return the possession (not the ownership) of a financial asset until the maturity of the loan. A reverse repo is a hypothecation 'in the reverse direction': creditor and debtor swap roles. In the investment markets When an investor asks a broker to purchase securities on margin, hypothecation can occur in two senses. First, the purchased assets can be hypothecated so that, if the investor fails to keep up credit repayments, the broker can sell some of the securities; the broker can also sell the securities if they drop in value and the investor fails to respond to a margin call. The second sense is that the original deposit the investor puts down for the margin account can itself be in the form of securities rather than a cash deposit, and again the securities belong to the investor but can be sold by the creditor in the case of a default. In both cases, unlike with consumer or business finance, the borrower does not typically have possession of the securities as they will be in accounts controlled by the broker, however, the borrower does still retain legal ownership. Rehypothecation Rehypothecation occurs mainly in the financial markets, where financial firms re-use the collateral to secure their own borrowing. For the creditor the collateral not only mitigates the credit risk but also allows refinancing more easily or at lower rates; in an initial hypothecation contract however, the debtor can restrict such re-use of the collateral. Re-hypothecation occurs when the creditor (a bank or broker-dealer) re-uses the collateral posted by the debtor (a client such as a hedge fund) to back the broker's own trades and borrowing. This mechanism also enables leverage in the securities market. In the UK, there is no limit on the amount of a client's assets that can be rehypothecated, except if the client has negotiated an agreement with their broker that includes a limit or prohibition. In the US, re-hypothecation is capped at 140% of a client's debit balance. In 2007, rehypothecation accounted for half the activity in the shadow banking system. Because the collateral is not cash it does not show up on conventional balance sheet accounting. Before the Lehman collapse, the International Monetary Fund (IMF) calculated that US banks were