Risk aversion and price limits in futures markets

Assuming that a representative trader is risk-neutral, Brennan [1986. Journal of Financial Economics 16, 213–233] shows that price limits, in conjunction with margins, may help reduce the default risk, lower the margin requirement, and decrease the total contract cost. We show that Brennan's result is true only when the trader's degree of risk aversion is low and the precision of additional information about the equilibrium futures price is also low. When the trader either is more risk-averse or can receive precise information, price limits become ineffective in either reducing the default probability, cutting down the margin requirement, or lowering the contract cost.     

大陆与台湾股指期货价格发现功能比较研究

本文利用日内15分钟交易数据,对大陆与台湾股指期货的价格发现功能进行了比较,发现沪深300股指期货和现货间存在双向价格引导关系,但在信息传导效率上,期货领先现货,对台湾市场而言,仅存在期货对现货的单向引导关系;期货市场在长期价格发现功能中占主导地位,但台指期货的主导作用要强于沪深300股指期货。文章从投资者结构、合约设计、交易制度等影响因素分析了两岸股指期货价格发现功能的差异,并提出改善大陆股指期货价格发现功能的建议。     

Setting the futures margin with price limits: the case for single-stock futures

Price limits are artificial boundaries established by regulators to establish the maximum price movement permitted in a single day. We propose using a new censoring method that incorporates the effect of price limits on the futures price distribution and investigates how to set an appropriate daily margin level using single-stock futures in Taiwan. We compare our estimations with those obtained using the method in Longin (J Bus 69:383–408, 1999). The results show that (1) the margin levels derived from the Longin method, which ignore price limits in the estimation, are lower than those in our censoring method; and (2) the legal margin for single-stock futures set at 13.5 % by the Taiwan Futures Exchange to avoid default risk appears to be too high.     

股指期货合约存续期价格引导关系的时变性研究

针对股指期货非季月合约存续期较短这一特点,按一定的标准将股指期货非季月合约2个月的存续期划分为合约上市期、主力合约期、非主力合约期、合约交割期等阶段,采用单位根检验、协整检验、格兰杰因果检验、脉冲响应分析等方法,利用各阶段5分钟或1分钟高频交易数据对股指现货、股指期货主力合约、股指期货非主力合约的价格引导关系进行实证分析,得出的结论是股指期货非季月合约在其存续期内的价格引导能力具有明显的时变性特征,股指期货和现货市场的跨市场监管者和交易者需要根据股指期货合约价格引导关系的时变性来合理制定自身的监管策略和交易策略。     

引入国债期货合约能否发挥现货市场稳定效应?——基于中国金融周期的研究视角

我国国债期货市场能否发挥稳定现货市场功能,金融周期风险是否会改变国债期货市场对现货市场波动的影响,是投资者实施风险管理和监管部门构建市场稳定机制的重要依据。本文通过信息传递机制和交易者行为两个维度探析国债期货市场发挥稳定功能的微观机理,分析金融周期风险对衍生工具稳定功能的影响,解析引入国债期货合约能否缓解金融周期波动对国债市场冲击,同时关注我国国债期货交易机制改进与现券波动关系。研究发现:(1)我国国债期货市场已实现抑制现货市场波动的功能,金融周期风险会引发现货价格波动,国债期货市场能够降低金融周期的波动冲击;(2)改善现货市场深度和套保交易是国债期货市场发挥稳定功能的微观路径,国债期货市场增进国债预期交易量流动性、减弱非预期交易量干扰,金融周期低波动区间套保交易稳定作用受到抑制;(3)国债期货投机交易和波动溢出效应助长现货市场波动,正负期现基差对国债波动影响具有非对称特征。     

Risk-Adjusted Day-of-the-Week, Day-of-the-Month, and Month-of-the-Year Effects on Stock Indexes and Stock Index Futures

This study uses risk-adjusted returns based on the Sharpe Performance Measure to evaluate the presence of three anomalies in two stock index futures, the futures of a smaller firm synthetic index, and their respective underlying spot indexes. The three anomalies are the day-of-the-week, the month-of-the-year, and the day-of-the-month effects. Using the nonparametric Kruskal-Wallis test, we find more evidence of day-of-the-week and day-of-the-month effects in futures index price behavior than in their underlying spot indexes. The January effect is found to be more pronounced for spot indexes than for stock index futures contracts. It is also more pronounced in the smaller firm synthetic index. Our results tend to disagree with efficient market proponents.     

限制交易政策如何影响期现关系?——对股指期货价格发现功能的实证检验

本文利用2015年中国股市大幅下跌期间,对股指期货严格限制交易政策这一独特事件前后的高频数据,研究限制交易政策对股指期货与股票市场价格引导关系的影响。利用I-S模型和分位数回归方法的实证结果表明:限制交易政策实施前,股指期货对股票市场的价格影响更强,尤其表现在价格急剧下跌时期;限制交易政策显著增加了期货市场交易成本,从而降低了期货市场的信息份额,削弱了其对股票市场的价格影响,并且改变了期货价格对现货价格“助跌强于助涨”的影响模式,增强了股指期货在价格上涨时对股票市场的影响。研究结果一方面直接量化了期货交易成本变动对其价格发现功能的负面影响,另一方面也从价格引导关系的视角提供了股市危机时期股指期货限制交易政策监管效果的实证证据。     

Information contents misjudged: Digressive convergence to equilibrium in cointegrated prices

The spot price on the Taiwan stock index is richer in information than the futures price judged by the price discovery measures of Gonzalo and Granger [Gonzalo, J., & Granger, C.W.J. (1995). Estimation of common long-memory components in cointegrated systems. Journal of Business and Economic Statistics, 13, 27–35.] and Hasbrouck [Hasbrouck, J. (1995). One security, many markets: Determining the contributions to price discovery. Journal of Finance, 50, 1175–1199.]. What is special about the markets is that both the spot and futures error-correction coefficients are positive, implying a digressive convergence to their long-run equilibrium in the error-correction (EC) process. Innovation accounting suggests that the cause of this digressive equilibrium adjustment is that investors systematically overreact to news in the less informative futures market but under-react to the more informative spot market. Our contribution is in identifying the digressive convergence implied by same-sign EC coefficients, comparing it to the normal convergence widely found in opposite-sign EC models, and providing short-run mispricing interpretations for both types of convergence to equilibrium.     

Informed Futures Trading and Price Discovery: Evidence from Taiwan Futures and Stock Markets

This article focuses on the information effects between the futures market and its spot market. Intraday data are used to investigate the lead-lag relationships between the returns and trading activity of Taiwan stock index futures and the spot returns. We focus on the transmission direction and the sources of information. Consistent with most previous studies, our results show that other than the contemporaneous relationship predicted by carry-cost theory and efficient market theory, futures returns significantly lead spot returns, which implies that informed trades may occur in the futures market. Using private transaction information, net open buy, as a proxy for futures trading activity and distinguishing different types of futures traders, we find that foreign institutional traders are the major source of informed trades because their trading has predictive power for future movements in both spot and futures prices. Traders in other categories are information laggards.     

Examining the forward pricing function of the Australian equity index futures contract

The relationship between the Australian equity index futures and spot prices is examined. Tests indicate that futures prices with one, two and three months to maturity are unbiased predictors of the spot and hence provide an efficient hedging mechanism for Australian equity index market participants, while six‐, nine‐ and twelve‐month futures prices are biased predictors of spot prices, indicating that speculative opportunities may exist in futures contracts for these time spreads. An analysis of the short‐run dynamic properties of the long‐run equilibrium relationship found that for all time spreads the futures prices respond to changes in the long‐run equilibrium, and for the twelve‐month contract, both futures and spot prices adjust to return to the long‐run equilibrium.     

中国股指期货合约乘数水平的研究

中国沪深500股指期货已经推出，其合约设计的合理与适用性则需要通过市场的实践来验证，在这其中，对合约乘数水平的检验至关重要，因为它与标的指数点住共同构成了合约的价值，进而直接影响到股指期货市场的稳定性。本文采用中国股指期贷合约推出后的真实交易数据、根据期货交易的一种风险控制理论“2N止损法”来测算投资者账户资产净值与头寸规模的绝对值，以此推导出现行合约乘数水平对投资者价格风险的影响程度，得出当前500元的合约乘数水平偏高的结论；并在此基础上，通过对中国股指期货市场的数据统计分析来检验以上结论，论证当前合约乘数水平的适用性，最后建议适当调整中国沪深500股指期货合约乘数的水平或尽快推出相应的小型合约。     

Does futures exhibit maturity effect? New evidence from an extensive set of US and foreign futures contracts

In a seminal article, Samuelson (1965) [Samuelson, P. A. (1965), “Proof that properly anticipated prices fluctuate randomly,” Industrial Management Review 6, 41-49.] proposes the maturity effect that the volatility of futures prices should increase as futures contract approaches maturity. This study provides new evidence on the maturity effect by examining a more extensive set of futures contracts than previous studies and analyzing each contract separately. Using 6805 futures contracts drawn from 61 commodities, including some data from non-US markets, we find that the maturity effect is absent in the majority of contracts. In addition, the maturity effect tends to be stronger in agricultural and energy commodities than in financial futures. We also examine the hypothesis in Bessembinder et al. (1996) [Bessembinder, H., J. F. Coughenour, P. J. Seguin, & M. M. Smoller (1996), “Is there a term structure of futures volatilities? Reevaluating the Samuelson hypothesis,” Journal of Derivatives 4, 45-58.], which states that negative covariance between the spot price and net carry cost causes the maturity effect in futures. Our results provide very weak evidence in favor of this hypothesis.     

Requiem for a market: an analysis of the rise and fall of a financial futures contract

Futures contracts often include a variety of delivery optionsthat allow participants flexibility in satisfying the contract.These options have the potential to broaden the appeal of thecontact. However, if these options are valuable, they may reducethe hedging effectiveness of the contract. This article analyzesthe GNMA CDR futures contract that appears to have failed becauseof flaws in the contract's design. For the first 6 years followingits introduction, the contract attracted significant and increasingvolume, but, subsequently, the volume declined to almost zero.Over the years during which the volume experienced its mostdramatic decline, the Treasury-bond futures contract provideda better hedge for current coupon GNMA securities than did theGNMA CDR futures contract. And, over this same period, the valueof the quality option embedded in the contract often exceeded5 percent of the futures price and reached a level of 19 percentat one point. We interpret the evidence to indicate that thecontract failed because the delivery options reduced the hedgingeffectiveness of the contract for current coupon mortgage securities.     

Investors’ preference towards risk: evidence from the Taiwan stock and stock index futures markets

We apply the stochastic dominance (SD) tests proposed by Linton et al. (2005) and Davidson and Duclos (2000) for risk averters and risk seekers to examine investors’ preferences with respect to the Taiwan stock index and its corresponding index futures. We find that there is no first‐order SD relationship between Taiwan spot and futures. However, for second‐ and third‐order SD, we find that spot dominates futures for risk averters whereas futures dominates spot for risk seekers. The implication is that to maximize their expected utilities, risk averters prefer to buy stocks, whereas risk seekers prefer long index futures.     

Futures and futures options with basis risk: theoretical and empirical perspectives

Under a no-arbitrage assumption, the futures price converges to the spot price at the maturity of the futures contract, where the basis equals zero. Assuming that the basis process follows a modified Brownian bridge process with a zero basis at maturity, we derive the closed-form solutions of futures and futures options with the basis risk under the stochastic interest rate. We make a comparison of the Black model under a stochastic interest rate and our model in an empirical test using the daily data of S&P 500 futures call options. The overall mean errors in terms of index points and percentage are ?4.771 and ?27.83%, respectively, for the Black model and 0.757 and 1.30%, respectively, for our model. This evidence supports the occurrence of basis risk in S&P 500 futures call options.     

Optimal clearing margin,capital and price limits for futures clearinghouses

We provide a model for a futures clearinghouse to use for setting optimal levels of clearing margin, capital and price limits, which minimizes the costs to clearing firms and simultaneously protects the clearinghouse from default by clearing firms. We show how to estimate the capital requirement, which supports the clearinghouse’s residual default risk that is not covered by the clearing margin. We apply our model to the Winnipeg Commodity Exchange and demonstrate that price limits reduce the sum of optimal clearing margin and capital to a level that is substantially lower than that required in the absence of price limits.     

A Likelihood Ratio Test of Price Volatilities: Comparing Stock Index Spot and Futures

This paper uses three methods to estimate the price volatility of two stock market indexes and their corresponding futures contracts. The classic variance measure of volatility is supplemented with two newer measures, derived from the Garman-Klass and Ball-Torous estimators. A likelihood ratio test is used to compare the classic variance measure of price volatilities of two stock market indexes and their corresponding futures contracts during the bull market of the 1980s. The stock market volatilities of the Standard & Poor's 500 (S&P 500) and New York Stock Exchange (NYSE) indexes were found to be significantly lower than their respective futures price volatilities. Since information may flow faster in the futures markets than in the corresponding stock market, our results support Ross's information-volatility hypothesis. It was also noted that the NYSE spot volatility was lower than the S&P 500 spot volatility. If the rate of information flow and firm size are positively related, then the lower NYSE spot volatility is explained by the size effect. The futures price volatilities for the two indexes were insignificantly different from each other. With stock index spot-futures price correlations approaching unity, one implication of our results for index futures activity is that smaller positions in futures contracts may suffice to achieve hedging or arbitrage goals.     

Price Limits and Margin Requirements in Futures Markets

This paper investigates the hypothesis that futures exchanges could use daily price limits as a substitute for higher margin requirements. The empirical results show that the size of margin is negatively correlated with the presence of price limits. Evidence points to the portfolio adjustment costs theory as an explanation of the benefits from price limits. The empirical results cast doubt on the notion that price limits should be abolished. The results also confirm that exchanges have set margin requirements according to economic theories.     

Beyond Basis Basics: Liquidity Demand and Deviations from the Law of One Price

Deviations from the law of one price between futures and spot prices—the futures-cash basis—capture information about liquidity demand for equity market exposure in global markets. We show that the basis comoves with dealer and investor futures positions, is contemporaneously positively correlated with futures and spot market returns, and negatively predicts futures and spot returns. These findings are consistent with the futures-cash basis reflecting liquidity demand that is common to futures and cash equity markets. We find persistent supply-demand imbalances for equity index exposure reflected in the basis, giving rise to an annual premium of 5% to 6%.     

Price Discovery Between Informationally Linked Markets During Different Trading Phases

The dynamic nature of the price information transfer when stock and futures markets switch between different price trading phases is examined. This is undertaken by decomposing Australian stock indexes and share price index futures contract data into bear- and bull-market phases and analyzing the change in the power of the bidirectional information feedback between the futures market and small, medium, and large stocks. Results support the hypothesis that the nature of the price-discovery process varies with the trading phase. In particular, during the bull phase small stocks show a marked increase in price exogeneity and futures prices contain relatively less price-sensitive fundamental information. We argue that in bull phases, futures trading becomes increasingly associated with noninformation trading such as realizing paper profits, portfolio rebalancing, and increased noise trading.