Stock market margin requirements and volatility: Implications for regulation of stock index futures

This article reexamines the evidence on the relationship between stock market margin buying and volatility, and discusses the implications for the regulation of futures markets margin requirements. Post-war data provide no evidence of a link between the initial margin requirements set by the Federal Reserve and stock market volatility. Over the entire period in which the Federal Reserve has set margin requirements (1934-present), there is a correlation between margin requirements and margin debt on the one hand and volatility on the other. However, margin debt is not primarily associated with downside volatility and margin requirements are not primarily associated with upside volatility, as would be expected if margin buying were the cause of the volatility. Thus, the experience with stock market margin requirements provides no support for regulating futures markets margins in order to curb volatility. While this evidence does not rule out the possibility that margin buying contributed to the speculative boom of the 1920s and the 1929 crash, margin debt represented a much greater fraction of the 1929 stock market than have stock market futures in the 1980s. Even taking the experience of the 1920s into account, therefore, there is still no justification for regulating futures margins in order to curb volatility.This article was prepared for the Columbia Center for the Study of Futures Markets Conference on Regulatory and Structural Reform of Stock and Futures Markets.     

Margin requirements and equilibrium asset prices

This paper studies the effect of margin requirements on asset prices and trading volume in a general equilibrium asset pricing model where Epstein-Zin investors differ in their degree of risk aversion. Under the assumptions of unit intertemporal elasticity of substitution and zero net supply of riskless assets, I show analytically that binding margin requirements do not affect stock prices. This result stands in contrast to previous partial equilibrium analysis where fixed margin requirements increase the volatility of stock prices. In this framework, binding margin requirements induce a fall in the riskless rate, increase its volatility, and increase stock trading volume.     

Margin regulation and volatility

An infinite-horizon asset-pricing model with heterogeneous agents and collateral constraints can explain why adjustments in stock market margins under US Regulation T had an economically insignificant impact on market volatility. In the model, raising the margin requirement for one asset class may barely affect its volatility if investors have access to another, unregulated class of collateralizable assets. Through spillovers, however, the volatility of the other asset class may substantially decrease. A very strong dampening effect on all assets׳ return volatilities can be achieved by a countercyclical regulation of all markets.     

An Empirical Analysis of Futures Margin Changes: Determinants and Policy Implications

Margin regulation raises two policy concerns. First, an alignment of margins to volatility can amplify procyclicality, leading to a build-up of excess leverage in good times and a forced deleverage in bad times. Second, competition among central counterparties (CCPs) can result in lower margin levels in order to attract more trading volume, which is referred to as a “race to the bottom.” Motivated by these issues, we empirically analyze the determinants of margin changes by using a data set of various futures margins from Chicago Mercantile Exchange (CME) Group. We first find that CME Group raises margins quickly following volatility spikes but does not immediately lower margins following volatility declines, implying that margin-induced procyclicality is more of a concern in recessions than in expansions. In addition, we find some evidence that the margin difference between CME Group and its competitor, Intercontinental Exchange (ICE), is an important driver of margin changes after changes in other margin determinants are controlled for, implying that competition may be factored into margin setting.     

Initial margin policy and stochastic volatility in the crude oil futures market

This article examines the relationship between the volatilityof the crude oil futures market and changes in initial marginrequirements. To closely match changes in futures market volatilitywith the corresponding changes in margin requirements, we inferthe volatility of the futures market from the prices of crudeoil futures options contracts. Using a mean-reverting diffusionprocess for volatility, we show that changes in margin policydo not affect subsequent market volatility.     

Leverage Is a Double-Edged Sword

We use proprietary data on intraday transactions at a futures brokerage to analyze how implied leverage influences trading performance. Across all investors, leverage is negatively related to performance, due partly to increased trading costs and partly to forced liquidations resulting from margin calls. Defining skill out-of-sample, we find that relative performance differentials across unskilled and skilled investors persist. Unskilled investors' leverage amplifies losses from lottery preferences and the disposition effect. Leverage stimulates liquidity provision by skilled investors, and enhances returns. Although regulatory increases in required margins decrease skilled investors' returns, they enhance overall returns, and attenuate return volatility.     

基于小波CCC-GARCH模型的融资融券交易与证券市场波动率关系研究

以2010年4月2日～2016年7月21日的中国证券市场交易数据为样本,运用小波CCC-GARCH模型,考量融资融券交易对证券市场波动率的影响.结果表明,融资交易行为对证券市场收益率和成交量的波动均有较显著的影响,而融券交易对市场波动率的影响不显著.同时,融资交易行为对市场的影响主要由高频信号所驱动,投资者短期非理性行为或噪音交易对市场波动的影响较大.为促进市场的健康发展,应均衡融资融券业务的发展,培养理性机构投资者,加强投资者风险警示加快融资融券数据库的建设.     

Information,hedging demand,and institutional investors: Evidence from the Taiwan Futures Exchange

This paper examines the effect of hedging demand by various types of institutional investor on subsequent returns and volatility. Using data from the Taiwan Futures Exchange, empirical results indicate that the hedging demand of foreign investors has a significant negative impact on subsequent returns and volatility. In addition, trading strategies based on the extreme hedging demand of foreigners are positively correlated with trading performance. Furthermore, there is evidence to show that returns (volatility) also affect the subsequent hedging demand of foreign investors, suggesting a feedback relation. Finally, the hedging demand of foreign investors has a greater impact on subsequent returns and volatility after global financial turmoil. Accordingly, this paper concludes that foreign investors are informed hedgers in the Taiwan futures market, especially after global financial turmoil.     

Stock market volatility and equity returns: Evidence from a two-state Markov-switching model with regressors

This paper proposes a two-state Markov-switching model for stock market returns in which the state-dependent expected returns, their variance and associated regime-switching dynamics are allowed to respond to market information. More specifically, we apply this model to examine the explanatory and predictive power of price range and trading volume for return volatility. Our findings indicate that a negative relation between equity market returns and volatility prevails even after having controlled for the time-varying determinants of conditional volatility within each regime. We also find an asymmetry in the effect of price range on intra- and inter-regime return volatility. While price range has a stronger effect in the high volatility state, it appears to significantly affect only the transition probabilities when the stock market is in the low volatility state but not in the high volatility state. Finally, we provide evidence consistent with the ‘rebound’ model of asset returns proposed by Samuelson (1991), suggesting that long-horizon investors are expected to invest more in risky assets than short-horizon investors.     

Interaction of investor trades and market volatility: Evidence from the Tokyo Stock Exchange

This paper examines the relation between market volatility and investor trades by identifying who supplies and demands market liquidity on the Tokyo Stock Exchange. Because the different trading patterns of various investor types such as individual investors, institutional investors, and foreign investors affect market liquidity differently, we find that market volatility fluctuates significantly depending on which investor types participate in trade. We show that market volatility increases by more than 50% from the average level when there are greater buy trades by momentum investors that demand liquidity and there are less sell trades by contrarian (or profit-taking) investors that supply liquidity. On the other hand, volatility dampens by more than 57% when there are greater sell trades by profit-taking investors, mostly by domestic investors, while there are less momentum buy trades.     

Margin Regulation and Stock Market Volatility

Using daily and monthly stock returns we find no convincing evidence that Federal Reserve margin requirements have served to dampen stock market volatility. The contrary conclusion, expressed in recent papers by Hardouvelis (1988a , b ), is traced to flaws in his test design. We do detect the expected negative relation between margin requirements and the amount of margin credit outstanding. We also confirm the recent finding by Schwert (1988) that changes in margin requirements by the Fed have tended to follow rather than lead changes in market volatility.     

流动性、风险收益与B股市场境外投资者行为

通过对B股市场的流动性、风险及国外投资者的投资动机进行了研究和度量后发现,B股市场对内开放的确加强了它的流动性,但是B股市场波动风险依然高于A股市场,且国外投资者投资B股市场受流动性变化影响不大,因为其他们投资的主要目的不是分散风险而是获取超额预期回报率。因而,在B股市场存废问题在短期内不能解决的情况下,加强B股市场管理,改善市场结构,对国外投资者的投资行为进行合理的监督和引导是完善B股市场的非常重要的举措。     

Idiosyncratic Volatility Covariance and Expected Stock Returns

Given that the idiosyncratic volatility (IDVOL) of individual stocks co‐varies, we develop a model to determine how aggregate idiosyncratic volatility (AIV) may affect the volatility of a portfolio with a finite number of stocks. In portfolio and cross‐sectional tests, we find that stocks whose returns are more correlated with AIV innovations have lower returns than those that are less correlated with AIV innovations. These results are robust to controlling for the stock's own IDVOL and market volatility. We conclude that risk‐averse investors pay a premium for stocks that pay well when AIV is high, consistent with our model.     

Expectations,Behavior, and Stock Market Volatility

Stock market volatility is caused by investors’ expectations and behavior. To study the implication relationship, on the one hand, we present an investor’s expectation-forming and decision-making model to summarize the key features of individual behavior. We think the individual expectation is determined mainly by the number of differences between positive signals and negative signals in the information flow. The behavior is determined by both the expectations of investors around him (her) and the expected returns from a potential action. On the other hand, we simulate an investor community to verify if the model is able to replicate the related stylized facts. Mainly, three conclusions are drawn from the simulation: (1) A relationship of asymmetrical conditional dependence exists between expectation consistency and behavior consistency. (2) Market volatility is caused mainly by the difference between expectation consistency and behavior consistency. As the density of connections in the investor community network increases, the difference between them grows. (3) Influential investors have profound impacts on the formation of normal investors’ expectations and behavior. Thus influential investors play an important role in determining the degree of market volatility.     

The Differential Impact of Federal Reserve Margin Requirements on Stock Return Volatility

This study examines the effect of changes in margin requirements on stock price volatility. We examine the possibility that the impact of margin requirements varies with a stock's degree of speculative interest. Using four alternative measures of speculative interest, we divide our sample into ten portfolios. We find no consistent evidence of a relationship between margin requirements and changes in volatility for any portfolio. The inconsistent and often contradictory results produced by these changes question its usefulness by Federal Reserve decision makers.     

The Asymmetric Relation Between Initial Margin Requirements and Stock Market Volatility Across Bull and Bear Markets

Higher initial margin requirements are associated with lowersubsequent stock market volatility during normal and bull periods,but show no relationship during bear periods. Higher marginsare also negatively related to the conditional mean of stockreturns, apparently because they reduce systemic risk. We concludethat a prudential rule for setting margins (or other regulatoryrestrictions) is to lower them in sharply declining marketsin order to enhance liquidity and avoid a depyramiding effectin stock prices, but subsequently raise them and keep them atthe higher level in order to prevent a future pyramiding effect.     

Animal Spirits,Margin Requirements,and Stock Price Volatility

A simple overlapping generations model is used to characterize the effects of initial margin requirements on the volatility of risky asset prices. Investors are assumed to exhibit heterogeneous preferences for risk-bearing, the distribution of which evolves stochastically across generations. This framework is used to show that imposing a binding initial margin requirement may either increase or decrease stock price volatility, depending upon the microeconomic structure behind fluctuations in economy-wide average risk-bearing propensity. The ambiguous effect on volatility similarly arises when the source of heterogeneity is noise trader beliefs.     

Ambiguous Information,Portfolio Inertia,and Excess Volatility

I study the effects of risk and ambiguity (Knightian uncertainty) on optimal portfolios and equilibrium asset prices when investors receive information that is difficult to link to fundamentals. I show that the desire of investors to hedge ambiguity leads to portfolio inertia and excess volatility. Specifically, when news is surprising, investors may not react to price changes even if there are no transaction costs or other market frictions. Moreover, I show that small shocks to cash flow news, asset betas, or market risk premia may lead to drastic changes in the stock price and hence to excess volatility.     

Asset Pricing with Dynamic Margin Constraints

This paper provides a novel theoretical analysis of how endogenous time‐varying margin requirements affect capital market equilibrium. I find that margin requirements, when there are no other market frictions, reduce the volatility and correlation of returns as well as the risk‐free rate, but increase the market price of risk, the risk premium, and the price of risky assets. Furthermore, margin requirements generate a strong cross‐sectional dispersion of stock return volatilities. The results emphasize that a general equilibrium analysis may reverse the conclusions of a partial equilibrium analysis often employed in the literature.     

Initial margin requirements and stock returns volatility: Another look

This article investigates the relationship between initial margin requirements and stock return volatility. Volatility is measured using a GARCH in Mean model. We find no evidence of an empirical relationship between margin requirements and the volatility of the S&P 500 index portfolio's excess returns. Evidence from short-sale data, and model sensitivity analysis are presented which support the hypothesis of no margin-volatility relationship. The results are consistent with the intertemporal CAPM model of Merton (1973) with an aggregate relative risk aversion measure of 4.1. In addition, we find evidence of long-term memory in conditional return distributions' volatility.The analysis and conclusions of this article are those of the author and do not indicate concurrence by other members of the research staff, by the Board of Governors, or by the Federal Reserve Banks.