Risk models only have value if they are used effectively in combination with limit management and control process. While a control function requires and relies on reports, the key is not generation of quantitative numbers, formatted in ten different variation and cuts; it is the interpretation and application of that analysis that matters. The objective of a risk function is to not just gather data, run reports, submit and analyze them, it is to ensure that unpleasant surprises and their impact is limited. While you can’t control the timing and magnitude of such surprises, a well managed and well run risk function can help manage expectations as well as plan ahead for unexpected shocks.
Limits play a major role in achieving that objective. But where do you start when you first review limits. How do you decide what is acceptable and what is not.
Ideally the limit setting process should be based on the following core principles.
- Before limit setting, a review of what is considered prudent risk and a review of normal business threshold for key risk measures should be completed. This sets the baseline level for limit calculations.
- Limits should be risk based, i.e. the measurement of limit utilization should be directly proportional to the amount of risk taken.
- Limits should be fungible at lower levels. The trader should be allowed to take risks to exploit the best opportunities available without being too tightly bound by complex rigid multi layered limit system. Similarly a senior trader should be allowed to move limits from one subordinate desk to another.
- Both hard and soft limits need to be set. If the limit is hard then traders know that they will be disciplined or fired for violating the limit. If the limit is soft a violation simply leads to documentation, exception reporting and a conversation where the trader is advised to reduce the position.
- If a portfolio is to be managed within a given set of limits, it should not be possible for changes in another portfolio to cause the limits for the former portfolio to be broken.
The Limit framework relies on both operational (stop loss, action trigger) and transactional (position, dealer, desk, product) limits. We take a look at both
Operational (exception or management action) Limits
Operational limits are generally exception limits that require immediate management action or intervention when the limit is breached and generally lead to a partial reduction or a closeout of the offending transaction.
Capital Loss & Stop loss limits
Stop loss limits act as a safety valve in case something starts to go wrong. Stop loss limits state that specified action must take place if the loss exceeds a threshold amount. Tight stop loss limits reduce the maximum possible loss and therefore reduce the capital required for the business. However, if the limits are too
tight they reduce the trader’s ability to make a profit.
The first step in setting stop loss limits is to determine the appetite of the company regarding its risk tolerance. This translates to specifying the amount of capital that the company can afford to lose.
Besides stop loss limits discussed above the following limits should also be set:
Inventory age limits
Inventory age limits set the time for which any security is held without being sold. This is to prevent traders from sitting on illiquid positions or positions with an unrecognized loss. The time allowed will depend on the overall purpose of the desk. If the desk is expected to trade in and out of the position quickly, the limits will be on the order of days. If the desk is expected to use long-term strategies then the limit can be on the order of weeks or months.
Concentration limits prevent traders from putting all the eggs in one basket. They ensure that the traders risk is not concentrated in one instrument or market. For example the equity desk may be limited to a maximum of 3% in any one company. This may also be subject to a limit on total percentage of that company’s equity that may be held.
While it is common to raise and approve exceptions to a transaction limit, a high frequency of such exceptions implies that the risk process and limit setting threshold need to be re-calibrated again. The calibration is required because either the market has moved to a different level of volatility and volume or the limits framework is out of touch or broken down and is no longer being taken seriously.
Exposure and sensitivity limits
Exposures limits are control limits that restrict the dollar amount that can be booked in a given day in any dealer, product, desk, tenor, risk combination.
Pre Settlement Risk (PSR) and Potential Future Exposure (PFE) Limits
PSR and PFE limits are product based counterparty limits that measure the worst case loss that is likely to occur if counterparties defaults prior to settlement of transaction. The worst case loss calculation assumes an unfavorable price movement, a client default and the cost of re-covering or squaring the transaction again from the open market.
For instruments that trade and are re-priced on a daily basis PSR and PFE consider the interaction of credit risk (a counterparty default) and price risk (the risk that the market has moved against us).
For example what happens when a counter party defaults on settlement when
He has to deliver a bond that you have purchased and
- bond prices have moved downwards
bond prices have moved upwards