A measure of the variability of a market factor, most often the price of the underlying instrument. Volatility is defined mathematically as the annualised standard deviation of the natural log of the ratio of two successive prices. The actual volatility realised over a period of time (the historical volatility) can be calculated from recorded data.
Volatility is one of the variables that must be specified in the Black-Scholes model of option pricing: a vanilla option will cost more when volatility is high than when it is low. However, volatility is the only one of these variables whose value must be estimated.
The estimate used (known as the implied volatility) can be derived from the prices of options in the market and the known input variables. However, the Black-Scholes model also assumes that volatility is constant, which is not true. New techniques have been developed to cope with volatility’s variability, including mean-reverting models (such as Garch) and stochastic volatility models.
* see also Black-Scholes model; Garch
The Energy Risk Glossary, now in its eighth edition, provides an at-a-glance explanation of the myriad specialised terms and acronyms used in energy trading and risk management.
This year, the guide has been updated by Aviv Handler of ETR Advisory. Energy Risk would like to thank him for his input into this edition, which benefits greatly from his valuable experience and insight into energy markets.
The fast-changing nature of these markets means much has changed since our last edition – almost 200 new entries and revisions have been made this year. Reflecting the increasing importance of regulation, definitions of the Markets in Financial Instruments Directive (MiFid) and the Ljubljana-based Agency for the Cooperation of Energy Regulators (Acer) make it into the glossary for the first time. A focus on improving back-office infrastructure and mitigating counterparty risk is also apparent from the inclusion of terms such as ‘portfolio reconciliation’ and ‘portfolio compression’.
The glossary is extensively cross-referenced, making for easy and thorough searches. We hope you find it useful.
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