why do we smile on the determinants of the implied volatility function abstract we report simple regressions and granger causality tests in order to understand the pattern of implied volatilities across exercise prices we employ all calls and puts transacted between 16 00 and 16 45 on the spanish ibex 35 index from january 1994 to april 1996 transaction costs proxied by the bid ask spread seem to be a key determinant of the curvature of the volatility smile moreover time to expiration the uncertainty associated with the market and the relative market momentum are also important variables in explaining the smile

a theory of input output architecture individual producers exhibit enormous heterogeneity in many dimensions this paper develops a theory in which the network structure of production who buys inputs from whom forms endogenously entrepreneurs produce using labor and exactly one intermediate input the key decision is which other entrepreneur s good to use as an input their choices collectively determine the economy s equilibrium input output structure generating large differences in size and shaping both individual and aggregate productivity when the elasticity of output to intermediate inputs in production is high star suppliers emerge endogenously this raises aggregate productivity as in equilibrium more supply chains are routed through higher productivity techniques

efficient mechanisms for bilateral trading we consider bargaining problems between one buyer and one seller for a single object the seller s valuation and the buyer s valuation for the object are assumed to be independent random variables and each individual s valuation is unknown to the other we characterize the set of allocation mechanisms that are bayesian incentive compatible and individually rational and show the general impossibility of ex post efficient mechanisms without outside subsidies for a wide class of problems we show how to compute mechanisms that maximize expected total gains from trade and mechanisms that can maximize a broker s expected profit journal of economic literature classification number 026

option pricing when the variance changes randomly theory estimation and an application in this paper we examine the pricing of european call options on stocks that have vari ance rates that change randomly we study continuous time diffusion processes for the stock return and the standard deviation parameter and we find that one must use the stock and two options to form a riskless hedge the riskless hedge does not lead to a unique option pricing function because the random standard deviation is not a traded security one must appeal to an equilibrium asset pricing model to derive a unique option pricing function in general the option price depends on the risk premium associated with the random standard deviation we find that the problem can be simplified by assuming that volatility risk can be diversified away and that changes in volatility are uncorrelated with the stock return the resulting solution is an integral ofthe black scholes formula and the distribution function for the variance of the stock price we show that accurate option prices can be computed via monte carlo simulations and we apply the model to a set of actual prices

the pricing of options on assets with stochastic volatilities one option pricing problem that has hitherto been unsolved is the pricing of a european call on an asset that has a stochastic volatility this paper examines this problem the option price is determined in series form for the case in which the stochastic volatility is independent of the stock price numerical solutions are also produced for the case in which the volatility is correlated with the stock price it is found that the black scholes price frequently overprices options and that the degree of overpricing increases with the time to maturity one option pricing problem that has hitherto remained unsolved is the pricing of a european call on a stock that has a stochastic volatility from the work of merton 12 garman 6 and cox ingersoll and ross 3 the differential equation that the option must satisfy is known the solution of this differential equation is independent of risk preferences if a the volatility is a traded asset or b the volatility is uncorrelated with aggregate consumption if either of these conditions holds the risk neutral valuation arguments of cox and ross 4 can be used in a straightfoward way this paper produces a solution in series form for the situation in which the stock price is instantaneously uncorrelated with the volatility we do not assume that the volatility is a traded asset also a constant correlation between the instantaneous rate of change of the volatility and the rate of change of aggregate consumption can be accommodated the option price is lower than the blackscholes b s 1 price when the option is close to being at the money and higher when it is deep in or deep out of the money the exercise prices for which overpricing by b s takes place are within about ten percent of the security price this is the range of exercise prices over which most option trading takes place so we may in general expect the b s price to overprice options this effect is exaggerated as the time to maturity increases one of the most surprising implications of this is that if the b s equation is used to determine the implied volatility of a near the money option the longer the time to maturity the lower the implied volatility numerical solutions for the case in which the volatility is correlated with the stock price are also examined the stochastic volatility problem has been examined by merton 13 geske 7 johnson 10 johnson and shanno 11 eisenberg 5 wiggins 16 and

interest rate volatility and the term structure a two factor general equilibrium model we develop a two factor general equilibrium model of the term structure the factors are the short term interest rate and the volatility of the short term interest rate we derive closed form expressions for discount bonds and study the properties of the term structure implied by the model the dependence of yields on volatility allows the model to capture many observed properties of the term structure we also derive closed form expressions for discount bond options we use hansen s generalized method of moments framework to test the cross sectional restrictions imposed by the model the tests support the two factor model there are essentially two approaches to the modeling of the term structure of interest rates in continuous time the equilibrium approach pioneered by

asymmetric private values auctions with application to joint bidding and mergers abstract much of the theoretical auction literature assumes that there are no observable differences between the bidders of an auction in this paper i present an asymmetric auction model where the distribution of a bidder s value depends on some commonly observed characteristics the model is applied to joint bidding and mergers in auction markets the results provide additional evidence that first price auctions are less susceptible to the acquisition and exercise of market power than open auctions

the informational content of implied volatility implied volatility is widely believed to be informationally superior to historical volatility because it is the markets forecast of future volatility but for s p 100 index options the most actively traded contract in the united states we find implied volatility in aggregate and across subsamples separated by maturity and strike price implied volatility has virtually no correlation with future volatility and it does not incorporate the information contained in recent observed volatility article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

trading mechanisms and stock returns an empirical investigation this paper examines the effects of the mechanism by which securities are traded on their price behavior we compare the behavior of open to open and close to close returns on nyse stocks given the differences in execution methods applied in the opening and closing transactions opening returns are found to exhibit greater dispersion greater deviations from normality and a more negative and significant autocorrelation pattern than closing returns we study the effects of the bid ask spread and the price adjustment process on the estimated return variances and covariances and discuss the associated biases we conclude that the trading mechanism has a significant effect on stock price behavior

an equilibrium model of bond pricing and a test of market efficiency in two previous and related papers 3 4 the authors have reported the results of estimating a particular equilibrium model of bond pricing using quarterly data on canadian government bonds for the period 1964 to 1979 this paper reports the results of applying a similar model to the pricing of u s government bonds for the period 1958 1979 using data from the crsp government bond file the paper also extends the previous empirical analysis by evaluating the ability of the pricing model to detect underpriced and overpriced bonds the data reveal a strong relation between price prediction errors and subsequent bond returns

stock volatility and margin trading abstract this study examines additions of otc issues to the list of marginable securities and tests the hypothesis that margin trading destabilizes prices and contributes to volatility no detrimental effects are found instead evidence suggests that margin eligibility increases the flow of information and enhances depth though volumes are 30 larger volatility and noise decrease with the inception of margin trading further margin eligibility is valuable increases in value of 2 occur upon the announcement of eligibility analysis of a small sample of margin eligibility revocations provides no evidence that tightening margin restrictions reduces volatility

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 after 55 years stock market margin requirements are again a source of controversy the securities and exchange act of 1934 transferred to the federal reserve system the authority exercised previously by the new york stock exchange and other private sector exchanges to set the minimum margins i e down payments that securities brokers and dealers subsequently expanded to all lenders must require of customers purchasing common stocks on credit the transfer of authority reflected the view widely held at the time that the low initial margins set by the exchanges had fueled the stock market boom of the 1920 s and that the frenzied liquidation of shares in response to margin calls had accelerated the crash in october 1929 supposedly dragging the economy down with it congress hoped that timely raising of margin requirements by the monetary authorities might dampen speculative excesses before they raged out of control or in today s terms that margin controls might reduce market volatility what the federal reserve has done since then with its margin setting authority can be seen from figure 1 which shows the time paths both of margins and one measure of market volatility from october 1934 to december 1987 margin requirements were set initially at 45 percent raised to 55 percent during the boomlet of 1936 and then cut back to a low of 40 percent after the sharp stockmarket break in the autumn of 1937 the requirement stayed at that level for the remainder of the 30 s and most of the war years but was stepped up sharply as the war drew to a close reaching 100 percent i e all cash no borrowing for most of 1946 changes were frequent over the next two and a half decades

reading the smile the message conveyed by methods which infer risk neutral densities abstract in this study we compare the quality and information content of risk neutral densities obtained by various methods we consider a non parametric method based on a mixture of log normal densities the semi parametric ones based on an hermite approximation or based on an edgeworth expansion the parametric approach of malz which assumes a jump diffusion for the underlying process and heston s approach assuming a stochastic volatility model we apply those models on ff dm exchange rate options for two dates models differ when important news hits the market here anticipated elections the non parametric model provides a good fit to options prices but is unable to provide as much information about market participants expectations than the jump diffusion model

supply chain disruptions evidence from the great east japan earthquake this paper quanti es the spillover eect of local exogenous shocks such as earthquakes to other rms through supply chain networks combining micro data on a large scale inter rm transaction network and geographic information on rm location we examine the rm level impact of supply chain disruptions occurring in the aftermath of the great east japan earthquake in 2011 when we focus on exiting rms in aected areas as the originating rms of spillovers we nd that sales growth of linked rms outside the area exhibits negative and signi cant eects for both upstream and downstream rms furthermore the signi cantly negative eects on downstream rms are shown not only for directly linked rms but also indirectly connected rms with degrees of separation 2 3 4 and 5

production networks and economic policy in this paper we show how to combine data on input output tables and recent insights from the theory of production networks in order to inform policy we first describe the information contained in input output tables compiled by statistical agencies and show how to derive relevant statistics of production networks we then discuss the implications of production networks for policy intervention in a series of domains such as fiscal policy industrial policy or finance finally we present a quantitative exercise applied to french data in order to illustrate that production networks shape the overall impact of competition policy on the economy

pricing european currency options a comparison of the modified black scholes model and a random variance model we use the modified black scholes model and a random variance option pricing model to study prices of european currency options traded in geneva the options which cannot be exercised early include calls and puts on the dollar swiss franc exchange rate in the empirical analysis we examine the model fit and the biases with respect to the strike price time to maturity and volatility there is some evidence of mispricing and there are small gains available by trading with the random variance model

initial margin policy and stochastic volatility in the crude oil futures market this article examines the relationship between the volatility of the crude oil futures market and changes in initial margin requirements to closely match changes in futures market volatility with the corresponding changes in margin requirements we infer the volatility of the futures market from the prices of crude oil futures options contracts using a mean reverting diffusion process for volatility we show that changes in margin policy do not affect subsequent market volatility

stochastic volatility option pricing this paper examines alternative methods for pricing options when the underlying security volatility is stochastic we show that when there is no correlation between innovations in security price and volatility the characteristic function of the average variance of the price process plays a pivotal role it may be used to simplify fourier option pricing techniques and to implement simple power series methods we compare these methods for the alternative mean reverting stochastic volatility models introduced by stein and stein 1991 and heston 1993 we also examine the biases in the black scholes model that are eliminated by allowing for stochastic volatility and we correct some errors in the stein and stein 1991 analysis of this issue empirical evidence on underlying asset prices and on their derivatives strongly suggests that asset price volatility is stochastic the pricing of options under this condition is therefore an important problem in this paper we study alternative option pricing methods that account for stochastic volatility we are particularly concerned with power series methods which we show to be quite accurate and easy to implement for alternative volatility specifications we point out their relation with recently proposed exact methods this permits a precise assessment of the approximation involved in the simple power series approach and of the impact of stochastic volatility on option prices following garman 1976 stochastic volatility option prices must satisfy a bivariate fundamental partial differential equation pde in the two state variables security price and volatility since volatility is not spanned by assets in the econ omy the volatility risk may not be eliminated by arbitrage methods therefore its market price explicitly enters into the pde the associated risk premium is owen graduate school of management vanderbilt university nashville tn 37203 and universita di siena facolta di scienza economiche e bancarie 53100 siena italy respectively part of this research was supported from a grant from the dean s fund and the financial markets research center at the owen school of management vanderbilt university some of this research was completed while roma was visiting the anderson graduate school of management ofthe university of california at los angeles we thank participants of the finance accounting and economics workshop at the owen school of management vanderbilt university for useful comments we appreciate the suggestions of roger huang craig lewis ron masulis and walter torous we thank joanne ball for editorial

stock price distributions with stochastic volatility an analytic approach we study the stock price distributions that arise when prices follow a diffusion process with a stochastically varying volatility parameter we use analytic techniques to derive an explicit closed form solution for the case where volatility is driven by an arithmetic ornstein ublenbeck or ar1 process we then apply our results to two related problems in the finance literature 1 options pricing in a world of stochastic volatility and 2 the relationship between stochastic volatility and the nature of fat tailes in stock price distributions article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

international money and stock market contingent claims abstract we develop a unified approach with closed form solutions for pricing bonds stocks currencies and their derivatives the specification assumes a fundamental risk factor represented by a stochastic positive definite matrix following a wishart autoregressive war process by assuming a volatility in mean specification for the domestic stock returns and the relative changes of exchange rates and a domestic stochastic discount factor exponential affine with respect to the fundamental risk it is possible to derive closed form solutions for the term structures of interest rates and for the risk neutral probabilities while keeping the flexibility of the model in particular i the domestic and foreign term structures are jointly affine and correspond to wishart quadratic term structures which can ensure the positivity of interest rates ii in this framework where the stock price follows a model with stochastic volatility we obtain explicit or quasi explicit formulas for futures and forward contracts swaps and options this extends results by heston 1993 and ball and roma 1994

price discrimination and bargaining empirical evidence from medical devices many important issues in business to business markets involve price discrimination and negotiated prices situations where theoretical predictions are ambiguous this paper uses new panel data on buyer supplier transfers and a structural model to empirically analyze bargaining and price discrimination in a medical device market while many phenomena that restrict price discrimination are suggested as ways to decrease hospital costs e g mergers group purchasing organizations and transparency i find that 1 non discriminatory pricing actually works against hospitals because competition is more intense under price discrimination and 2 results depend ultimately on a previously unexplored bargaining effect

overreactions in the options market this paper examines the term structure of options implied volatilities using data on s p 100 index options because implied volatility is strongly mean reverting the implied volatility on a longer maturity option should move by less than one percent in response to a one percent move in the implied volatility of a shorter maturity option empirically this elasticity turns out to be larger than suggested by rational expectations theory long maturity options tend to overreact to changes in the implied volatility of short maturity options are investors rational do they behave like bayesian statisticians when it comes to incorporating new information into asset prices proponents of the efficient markets hypothesis would answer this question in the affirmative many others however believe that bayesian rationality is a poor description of investor behavior and that as a consequence asset prices tend to be informationally inefficient one way in which inefficiencies might arise is through the overreactions of traders to the arrival of new information 1 this possibility is raised by experimental and survey findings which indicate that people have a systematic tendency to overemphasize recent data at the expense of other information when making projections 2 the objective of this paper is to search for evidence of such overreactive behavior in a semingly peculiar place the options market options may appear to be unlikely candidates for overreaction because unlike primary securities their prices are closely tied down by arbitrage considerations as black and scholes 1973 demonstrate if stock price volatility is known options prices are completely determined any deviation from the prescribed value implies a riskless profit opportunity however given that volatility is in fact unknown and changing options do retain something of an independent nature not wholly redundant with their underlying stocks options can be thought of as reflecting a speculative market in volatility the implied volatility on a given option obtained by inverting a

merger review with intermediate buyer power abstract buyer power features prominently in antitrust cases and debates particularly as it relates to the potential for a merger among suppliers to harm a buyer using a myersonian mechanism design approach loertscher and marx 2019b provide a framework for merger review for markets with buyer power assuming that buyer power is a zero one variable in the present paper we extend this analysis by treating buyer power as a continuous variable technically as a ramsey weight that ranges from zero to one this generalization is relevant because among other reasons the ramsey weight can be interpreted as a conduct parameter that can be estimated moreover we establish the robustness of prior results to an alternative way of modelling merger related cost synergies and we show that when an acquiring firm s choice of target is endogenous its profit maximizing choice depends on the buyer s power

mergers when prices are negotiated evidence from the hospital industry in recent years many hospitals have merged in part to gain bargaining leverage with managed care organizations mcos we investigate the price impact of hospital mergers by formulating and estimating an equilibrium bargaining model between hospital systems and managed care health insurers over prices for inpatient services we estimate the parameters of the model using claims and discharge data from northern virginia in 2006 inova health system proposed to acquire prince william hospital we nd that this merger would have raised prices signicantly and that the remedy of separate bargaining imposed by the ftc in a separate hospital case would have resulted in a larger price increase

the behavior of the volatility implicit in the prices of stock index options abstract we examine stock market volatility around the quarterly expirations of stock index futures contracts and nonquarterly expirations of stock index options using estimates of the volatility implicit in the option prices the option prices reflect increases in the volatility of the underlying stock indexes around both quarterly and nonquarterly expiration dates analysis of the residual returns on index options provides evidence consistent with an unexpected increase in market volatility around expiration dates

long and plosser meet bewley and lucas abstract we develop an n sector business cycle network model a la long and plosser 1983 featuring heterogenous money demand a la bewley 1980 and lucas 1980 despite incomplete markets and a well defined distribution of real money balances across heterogeneous households the bewley lucas long plosser model remains analytically tractable with closed form solutions relying on the tractability we establish several important results i the economy s input output network linkages become endogenously time varying over the business cycle thanks to the endogenous time varying distribution of money demand and its influence on cross sector allocations of commodities ii despite flexible prices transitory money injections can generate highly persistent effects on sectoral output also thanks to the time varying distribution of money demand and its effect on input output coefficients iii although money injection is distributed equally across households by design the real effects are asymmetric across production sectors e g the impact of money is strongest on downstream sectors that purchase intermediate goods from the rest of the economy but weakest on upstream sectors that supply intermediate goods to the other sectors in sharp contrast to the case of sectoral technology shocks and government spending shocks our model also provides a micro foundation for the labor wedge and shows that movements in the distribution of money demand can explain the cyclical behavior of the labor wedge

margin requirements and stock market volatility abstract it has long been recognized that margin requirements through leverage affect the volume of speculative activity controlling speculative behavior is one approach to inhibiting overvaluation in stocks and reducing the potential for a precipitate price decline fueled by the involuntary selling that stems for example from margin calls

a theory of the nominal term structure of interest rates a model of the nominal term structure of interest rates is developed that has a positive and stationary process for the interest rate and delivers closed form expressions for the prices of discount bonds and european options on bonds unlike the one state variable version of the cox ingersoll and ross 1985 model this model even in its one state variable version allows the term premium to change sign as a function of the state and the term to maturity and also allows for shapes of the yield curve that are observed in the u s data but that are disallowed in the cox ingersoll and ross model article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

the welfare effects of bundling in multichannel television markets we measure how the bundling of television channels affects short run welfare we estimate an industry model of viewership demand pricing bundling and input market bargaining using data on ratings purchases prices bundles and input costs we conduct simulations of a la carte policies that require distributors to offer individual channels for sale to consumers we estimate that negotiated input costs rise by 103 0 percent under a la carte these higher input costs offset consumer benefits from purchasing individual channels mean consumer and total surplus change by an estimated 5 4 to 0 2 percent and 1 7 to 6 0 percent respectively jel d12 l11 l51 l82 m31

option pricing when the variance is changing the monte carlo method is used to solve for the price of a call when the variance is changing stochastically

the irrelevance of margin evidence from the crash of 87 following the crash of 1987 one contentious regulatory issue has been whether margin activity exacerbated the decline in equity values we contrast the crash behavior of nasdaq securities eligible for margin trading with the behavior of ineligible ones consistent with the hypothesis that margin eligible securities were more frequently subjected to margin calls and forced sales we find that abnormal volumes were uniformly larger for eligible securities however there is no evidence that this activity provoked additional price depreciation margin eligible securities actually fell by one percent less than the ineligible securities over the period

american options under stochastic volatility the problem of pricing an american option written on an underlying asset with constant price volatility has been studied extensively in literature real world data however demonstrate that volatility is not constant and stochastic volatility models are used to account for dynamic volatility changes option pricing methods that have been developed in literature for pricing under stochastic volatility focus mostly on european options we consider the problem of pricing american options under stochastic volatility which has had relatively much less attention from literature first we develop a transformation procedure to compute the optimal exercise policy and option price and provide theoretical guarantees for convergence second using this computational tool we explore a variety of questions that seek insights into the dependence of option prices exercise policies and implied volatilities on the market price of volatility risk and correlation between the asset and stochastic volatility the speed and accuracy of the procedure are compared against existing methods as well

stochastic volatility movements in short term interest rates and bond option values abstract two classes of models for pricing interest rate contingent claims are compared the first contains standard single factor models while the second includes stochastic volatility variants of these it is demonstrated that incorporating stochastic volatility significantly improves the ability of the models to fit movements in short term interest rates the fundamental reason for this is that standard univariate models do not generate enough conditional heteroskedasticity the models are also compared on the basis of bond option prices when each is constrained to fit a particular yield curve the results suggest that stochastic volatility models will typically produce lower option values than corresponding single factor models particularly for near the money to deep out of the money options this is because estimated historical volatilities are significantly lower under stochastic volatility when single factor models are constrained to the same level of volatility as implied by stochastic volatility models in most cases the pricing differences become minor

targeted carbon tax reforms abstract in the presence of intersectoral linkages sector specific carbon tax changes can have complex general equilibrium effects in particular a carbon tax on the emissions of a sector can lead to an increase in aggregate emissions we analytically characterise how incremental taxes on the emissions of any set of sectors affect aggregate emissions we show that carbon tax reforms that target sectors based on their position in the production network can achieve a greater reduction in aggregate emissions than reforms that target sectors based on their direct emissions alone we illustrate the effects of carbon tax reforms by calibrating our intersectoral network model to the economies of two countries

vertical specialization and gains from trade multi stage production is widely recognized as an important feature of the modern global economy this feature has been incorporated into many state of the art quantitative trade models and has been shown to deliver significant additional gains from international trade

cross sectional dependence and problems in inference in market based accounting research this paper provides a framework and some empirical evidence to evaluate the seriousness of problems in inference that arise in stockreturn based studies when the data are cross sectionally dependent the study is motivated on the grounds that statistical procedures designed to address such problems are often infeasible and even when they can be implemented they sometimes introduce other more serious difficulties thus researchers have frequently adopted an approach that ignores the cross sectional dependence e g ordinary least squares ols the objective of this paper is to help identify the contexts in which ignoring the dependence would lead to serious misstatement of significance levels cross sectional dependence in stock returns data is likely to exist when at least some of the returns are sampled from common time periods this would be the case in all studies of the reaction of stock prices to a

option values under stochastic volatility theory and empirical estimates abstract this paper numerically solves the call option valuation problem given a fairly general continuous stochastic process for return volatility statistical estimators for volatility process parameters are derived and parameter estimates are calculated for several individual stocks and indices the resulting estimated option values do not differ dramatically from black scholes values in most cases although there is some evidence that for longer maturity index options black scholes overvalues out of the money calls in relation to in the money calls

the creation and resolution of market uncertainty the impact of information releases on implied volatility we model and examine the impact of information releases on market uncertainty as mea sured by the implied standard deviation isd from option markets distinguishing between scheduled and unscheduled announcements we hypothesize that since the timing although not the content of scheduled announcements is known a priori the pre release isd will impound the anticipated impact of important releases on price volatility and that the isd will normally decline post release as this uncertainty is resolved conversely we hypothesize that the unexpected high volatility caused by major unscheduled releases will cause market participants to adjust upward their estimates of likely volatility over the remaining life of the option resulting in an increase in the isd our evidence supports both hypotheses the isds that we consider are from the t bond eurodollar and deutschemark options markets we examine scheduled macroeconomic news releases such as the employment report and the ppi we also find that the observed tendency for the isd to fall on fridays and rise on mondays is due to the weekday pattern of scheduled news releases

the relevance of margin regulations note margin credit was singled out for selective credit control in 1934 by the securities exchange act sea this act directed the federal reserve board to regulate security credit so as to prevent the excessive use of credit in the purchase or carrying of securities the principal objectives of the sea were 1 to protect investors from speculative losses 2 to prevent the speculative securities markets from absorbing credit away from productive commercial and agricultural uses and 3 to inhibit security price fluctuations due to credit financed security purchases to date there has been little research into the effectiveness of margin regulations in attaining the objectives of the sea 2 one noteworthy exception is a paper by luckett 1982 which analyzes the efficacy of margin requirements in influencing the investor s degree of personal leverage and risk exposure however luckett s analysis leaves unanswered the impacts of changes in margin requirements on firm valuation security returns uncertainty and the allocation of credit in the economy in this paper modern finance theory is employed to analyze some of these effects we conclude that corporations will take actions so as to offset at least in part the impacts of changes in margin restrictions on personal leverage and that the effects of margin requirements are generally inconsistent with the objectives of the sea reformers

derivative pricing with wishart multivariate stochastic volatility this paper deals with the pricing of derivatives written on several underlying assets or factors satisfying a multivariate model with wishart stochastic volatility matrix this multivariate stochastic volatility model leads to a closed form solution for the conditional laplace transform and quasi explicit solutions for derivative prices written on more than one asset or underlying factor two examples are presented i a multiasset extension of the stochastic volatility model introduced by heston 1993 and ii a model for credit risk analysis that extends the model of merton 1974 to a framework with stochastic firm liability stochastic volatility and several firms a bivariate version of the stochastic volatility model is estimated using stock prices and moment conditions derived from the joint unconditional laplace transform of the stock returns

margin adequacy and standards an analysis of the crude oil futures market this article proposes two value based standards for setting the initial margin requirements on futures positions based on the observation that the distributions of the payoffs to futures traders and the potential losses to the futures clearinghouse can be described in terms of the payoffs to barrier options using both margin standards we examine the adequacy of initial margin requirements in the crude oil futures market our results suggest that on average the initial margin requirements set by the new york mercantile exchange exceed the minimum margins required under our option based standards for adequacy

auctions versus negotiations which is the more profitable way to sell a company an auction with no reserve price or an optimally structured negotiation with one less bidder we show under reasonable assumptions that the auction is always preferable when bidders signals are independent for affiliated signals the result holds under certain restrictions on the seller s choice of negotiating mechanism the result suggests that the value of negotiating skill is small relative to the value of additional competition the paper also shows how the analogies between monopoly theory and auction theory can help derive new results in auction theory jel d44 g34 there are close analogies between standard price theory and the theory of auctions in an absolute english auction in which the price rises continuously until only one bidder remains and the seller is required to accept the final bid the sale price equals the lowest competitive price at which supply equals demand in the theory of optimal auctions the seller is treated as a monopolist who can choose any

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 beyond their prudential functions the effects of initial margin requirements on securities markets are not well understood many have argued based upon empirical findings that the level of margin requirements has no discernable impact on stock price behavior nevertheless the view that high margin requirements dampen speculative excesses and reduce excess price volatility remains popular the simultaneous existence of such views highlights the uncertainty surrounding this issue in fact there exists no rigorously articulated theory of the interaction between initial margin requirements and stock prices and their returns characteristics in this paper we construct a simple dynamic model useful for characterizing the effects of initial margin requirements on security prices and returns to analyze the impact of margins we introduce investor heterogeneity into an otherwise simplified overlapping generations olg economy 2 the olg models are constructed so that each generation displays heterogeneous preferences or beliefs the distribution of which evolves stochastically across generations in each of two heterogeneous taste models we consider there are two types of agents one of which is more risk tolerant than the other in one model the

the pricing of japanese equity warrants discrepancies between the black scholes value of japanese equity warrants and their observed prices are explained in part by the stochastic volatility of changes in prices of the underlying stocks we fit garch and egarch models to the stochastic volatility and briefly compare their performance to the cev model a hopscotch algorithm is used to value the warrants in the presence of the stochastic stock price volatility the stochastic volatility hopscotch warrant values still differ substantially from corresponding prices in contrast away from the money short term nikkei 225 options valued with the same stochastic volatility models are close to observed prices a regression model is used to fit the differences between warrant values and prices as a function of proxies for market impediments

modeling the effects of mergers in procurement in procurement settings mergers among suppliers reduce buyers choice sets and can harm buyers by eliminating their preferred supplier or reducing their negotiating leverage i develop a stochastic economic model that predicts the effects of mergers based on information that commonly is available to antitrust authorities i derive general expressions for the ex ante expected changes in price buyer utility and supplier profit each becomes tractable under certain distributional assumptions the model predicts that average prices will increase by more than 40 due to the recently litigated acquisition of power reviews by bazaarvoice in the absence of an effective remedy

some empirical evidence on stock returns and security credit regulation in the otc equity market abstract this paper studies price reactions of otc stocks that are added to and deleted from the federal reserve board s official list of otc margin stocks we interpret any price reactions as economic effects related to the fed s security credit regulatory activities under the 1969 amendment to the 1934 securities exchange act we test for three effects 1 fed endorsement 2 credit and 3 asymmetric information using both weekly and daily data we find strong positive stock price reactions when otc stocks are added to the fed s list no major effects are discernible when stocks are removed from the fed s list we interpret these findings to be consistent with a credit convenience effect