The decomposition of risks and returns into overnight and intraday components is an emerging area of research. In this post, we examine how these components differ in terms of volatility clustering and the variance risk premium, and what this implies for forecasting, risk management, and strategy design.
Breaking Down the Volatility Risk Premium: Overnight vs. Intraday Returns
The decomposition of the volatility risk premium (VRP) into overnight and intraday components is an emerging area of research. Most studies indicate that the VRP serves as compensation for investors bearing overnight risks.
Reference [1] continues this line of research, with its main contribution being the decomposition of the variance risk premium into overnight and intraday components using a variance swap approach. The study also tests the predictive ability of these components and examines the seasonality (day-of-week effects) of the VRP.
Findings
-The paper decomposes the variance risk premium into overnight and intraday components across the US, Europe, and Asia.
-It finds that the variance risk premium is significantly negative during the overnight non-trading period.
-During the intraday trading period, the variance risk premium becomes positive and often insignificant.
-The results show that the overall negative variance risk premium documented in prior studies is largely driven by the overnight component.
-The study uses the P&L of a hypothetical variance swap to analyze these components.
-The intraday variance risk premium captures short-term risk and has predictive power over 1 to 3-month horizons.
-The overnight variance risk premium reflects longer-term risk and shows predictive ability over 6 to 12-month horizons.
-The findings highlight the importance of non-trading periods in explaining the behavior of the variance risk premium.
In summary, the study reaffirms that the variance risk premium is significantly negative during the non-trading overnight period, while it becomes positive and often insignificant during the intraday trading period.
An interesting finding is the day-of-week seasonality. For instance, going long volatility at the open and closing the position at the close tends to be profitable on most days, except Fridays.
Reference
[1] Papagelis, Lucas and Dotsis, George, The Variance Risk Premium Over Trading and Non-Trading Periods (2024). SSRN 4954623
Intraday and Overnight Volatility Clustering Effect
Volatility clustering is a phenomenon observed in financial markets where periods of high volatility tend to cluster together, followed by periods of low volatility. This pattern suggests that extreme price movements are not randomly distributed over time but rather occur in clusters or groups.
Volatility clustering has undergone extensive study within the daily timeframe. Reference [2] delves into volatility clustering within intraday and overnight timeframes. It specifically investigates clustering within each timeframe and between them.
Findings
-The paper studies volatility clustering in intraday and overnight returns across 15 global equity markets.
-It finds that volatility clustering is present in both intraday and overnight returns across multiple time scales, from daily to long-term horizons.
-The results show that volatility clustering is generally stronger in overnight returns than in intraday returns.
-Cross clustering between intraday and overnight volatility is relatively weak within each market, especially at shorter time scales.
-The findings are consistent across both developed and emerging markets, indicating a universal pattern.
-The study highlights the importance of considering both short-term and long-term risks in equity markets.
-The results suggest that volatility dynamics differ between trading and non-trading periods.
-The paper provides implications for trading and risk management strategies based on volatility clustering behavior.
In short, the paper shows that volatility clustering is a universal feature of both intraday and overnight returns across multiple time scales. It also finds that clustering is stronger overnight, while cross-effects between intraday and overnight volatility remain weak, with consistent patterns across global markets.
Reference
[2] Xiaojun Zhao, Na Zhang, Yali Zhang, Chao Xu, Pengjian Shang, Equity markets volatility clustering: A multiscale analysis of intraday and overnight returns, Journal of Empirical Finance 77 (2024) 101487
Closing Thoughts
Taken together, these studies show that volatility dynamics differ significantly between intraday and overnight periods, both in terms of risk pricing and clustering behavior. The variance risk premium is largely driven by the overnight component, while intraday and overnight volatility exhibit distinct clustering patterns with limited interaction. These findings highlight the importance of separating trading and non-trading periods in both forecasting and risk management, as each captures different horizons and sources of risk, offering more refined inputs for portfolio construction and strategy design.
