lottery dependent utility in this paper we propose a model for decision making under risk that is capable of predicting empirically observed preference patterns that have been found to be incompatible with the expected utility model the model departs from the classical expected utility model by allowing utilities to depend on the lottery the dependence of utilities on the lottery being evaluated is achieved by restricting the utility measure to a convenient parametric family of functions the idea then is to use each lottery to determine a specific parameter value thus characterizing the utility function for each particular lottery the expected value of this lottery dependent utility function provides the overall measure of preference the model retains the properties of transitivity stochastic dominance and continuity it also permits types of analyses such as exploitation of basic attitudes toward risk through risk aversion properties that have been found useful in decision theory the primary use of our model is in descr

liquidity shocks size and the relative performance of hedge fund strategies abstract we examine whether the increase in the flow of capital to hedge funds over the period 1994 2005 had a negative impact on performance more specifically we study the relative performance of small versus large funds for each of the hedge fund strategies our results indicate that on an absolute return basis small funds outperform large funds on a risk adjusted return basis however we find that large funds outperform small funds and that large funds are also shown to hold less liquid assets and take on less systematic and idiosyncratic risk than small funds further funds that experience positive liquidity shocks generally outperform those that experience negative liquidity shocks we also find evidence that hedge fund managers that are aggressive in dealing with liquidity shocks perform better than hedge fund managers that are conservative in dealing with liquidity shocks

buyers pricing behavior for risky alternatives encoding processes and preference reversals numerous studies have examined individuals minimum selling prices or certainty equivalents for lotteries as measures of preference but few have examined maximum buying prices because every transaction involves a buyer as well as a seller buyers pricing behavior is of interest in its own right two prospect theory based descriptive models of maximum buying prices the integration and segregation models are developed from different assumptions about cognitive encoding processes the models were tested experimentally using an incentive compatible cash payoff scheme in which maximum buying prices for bets and choices between bets were elicited from subjects surprisingly observed maximum buying prices were far below expected values even for bets with probabilities of winning near 1 0 this suggests buyers are strongly influenced by loss aversion and that the conventional assumption that the buying price for a risky alternative is a reduction in the alternative s payoffs fails to describe behavior instead it appears subjects predominately employed a segregation encoding process in which the buying price was encoded separately from the bet s payoffs and treated as a sure loss however an additional result was not explained adequately by either encoding model buying prices were less risk averse than choices for 3 expected value bets creating preference reversals of the standard kind lichtenstein and slovic 1971 but more risk averse for 100 expected value bets creating reverse preference reversals casey 1991 implications for the scale compatibility principle tversky et al 1988 are discussed two theoretical approaches are outlined which offer promise in the development of a unified model of price judgments and choice preferences under risk

disappointment in decision making under uncertainty decision analysis requires that two equally desirable consequences should have the same utility and vice versa most analyses of financial decision making presume that two consequences with the same dollar outcome will be equally preferred however winning the top prize of 10 000 in a lottery may leave one much happier than receiving 10 000 as the lowest prize in a lottery this paper explores the implications of disappointment a psychological reaction caused by comparing the actual outcome of a lottery to one s prior expectations for decision making under uncertainty explicit recognition that decision makers may be paying a premium to avoid potential disappointment provides an interpretation for some known behavioral paradoxes and suggests that decision makers may be sensitive to the manner in which a lottery is resolved the concept of disappointment is integrated into utility theory in a prescriptive model

a complete characterization of optimal growth paths in an aggregated model with a non concave production function the convexity of technology has played a crucial role in economic analyses of optimal one sector growth problems for example two of the key results on the traditional model of ramsey 1928 that have relied on the convexity of the technology are that optimal intertemporal growth involves moving monotonically towards a unique steady state as in cass 1965 koopmans 1965 and that the value function is a concave differentiable function of the initial capital stock as in benveniste and scheinkman 1979

ssb and weighted linear utility as expected utility with suspicion we show that a suspicious subjective expected utility seu maximizer i e one who treats potential consequences of states as information useful in assessing the probability of those states may under reasonable circumstances act as though he were maximizing either weighted linear utility or skew symmetric bilinear ssb utility seu with suspicion therefore explains at least as many empirical violations of seu theory as do these and similar models we give examples to illustrate how several important types of seu violations may seem to arise when suspicion is present

induced preferences nonadditive beliefs and multiple priors we study a decision maker who follows the savage axioms we show that if he or she is able to take unobservable actions that influence the probabilities of outcomes then it can appear to an outsider as if his or her subjective probabilities are nonadditive implications for multiperiod decision are explored we extend the model to include a second individual who is also able to take a hidden action we show that this may induce uncertainty averse preferences over some class of acts even if the second individual acts to help the decision maker with high probability

a two sector model of endogenous growth with leisure in this paper we analyze a class of endogenous growth models with physical and human capital and with three altematives uses of time unqualified leisure work and education in contrast to some other related models we find that even in the absence of technological extemalities there could be multiple balanced paths we provide a characterization of the qualitative behavior of consumption leisure work and education over those balanced paths and study their transitional dynamics

investment tax incentives prices and the supply of capital goods using data on the prices of capital goods this paper shows that much of the benefit of investment tax incentives does not go to investing firms but rather to capital suppliers through higher prices the reduction in the cost of capital from a 10 percent investment tax credit increases equipment prices 3 5 7 0 percent this lasts several years and is largest for assets with large order backlogs low import competition or with a large fraction of buyers able to use investment subsidies capital goods workers wages rise too instrumental variables estimates of the short run supply elasticity are around 1 and can explain the traditionally small estimates of investment demand elasticities in absolute value the demand elasticity implied here exceeds 1

an anatomy of the s p game the effects of changing the rules this study analyzes the effects of changes in s p 500 index composition from january 1986 through june 1994 a period during which standard and poor s began its practice of preannouncing changes five days beforehand the new announcement practice has given rise to the s p game and has altered the way stock prices react we find that prices increase abnormally from the close on the announcement day to the close on the effective day the overall increase is greater than under the old announcement policy although part of the increase reverses after the stock is included in the index the s p game is based upon the perceived price reaction of a stock to news that it will be added to the s p 500 the game involves buying the shares of the stock ahead of s p 500 funds and then selling after index fund demand is satisfied the opportunity to play the s p game arose in october 1989 when standard and poor s p began its practice of preannouncing changes to the s p 500 before that time s p announced the change in composition after the close of trading with the change becoming effective by the following morning s open with no lead time index funds bought the shares of the newly included stock on the day following the announcement the buying pressure caused prices to rise for additions during the period 1976 through 1983 for example shleifer 1986 found an abnormal price increase of 2 79 percent on the day following the announcement using roughly the same sample period harris and gurel 1986 reported a 3 13 percent average increase

the effect on stock price of inclusion in or exclusion from the s p 500 1987 the effect on stock price of inclusion in or exclusion from the s p 500 financial analysts journal vol 43 no 1 pp 58 65

new evidence on stock price effects associated with changes in the s p 500 index since october 1989 standard and poor s has when possible announced changes in the composition of the s p 500 index one week in advance because index funds hold s p 500 stocks to minimize tracking error index composition changes since this date provide an opportunity to examine the market reaction to an anticipated change in the demand for a stock using post october 1989 data the authors document significantly positive negative postannouncement abnormal returns that are only partially reversed following additions deletions these results indicate the existence of temporary price pressing and downward sloping long run demand curves for stocks and represent a violation of market efficiency copyright 1997 by university of chicago press

an investigation of transactions data for nyse stocks using transactions data the behavior of returns and characteristics of trades at the micro level is examined a minute by minute market return series is formed and tested for normality and autocorrelation evidence of differences in return distributions is found among overnight trades trades during the first 30 minutes following the market opening trades at the close and trades during the remainder of the day the latter distribution is found to be normal unusually high returns and standard deviations of returns are found at the beginning and the end of the trading day when the beginningand end of the day effects are omitted autocorrelation in the market return series is reduced substantially a number of patterns in trading are reported this paper empirically investigates the nature of the return generating process and the characteristics of trade size price changes trading frequency and trading interval at the level of individual trades for a large sample of nyse stocks previous studies of market indices have used daily weekly or monthly

market microstructure and securities values evidence from the tel aviv stock exchange abstract this paper examines the value effects of improvements in the trading mechanism selected stocks on the tel aviv stock exchange were transferred gradually from a daily call auction to a mechanism where the call auction was followed by iterated continuous trading sessions this event was associated with a positive and permanent price appreciation the cumulative average market adjusted return over a period that started five days prior to the announcement and ended 30 days after the stocks started trading by the new method was approximately 5 5 in addition we find positive liquidity externalities spillovers across related stocks and improvements in the value discovery process due to the improved trading method finally there was a positive association between liquidity gains and price appreciation

changes in the standard and poor s 500 list l harris and e gurel 1986 and a shleifer 1986 examined changes in the standard and poor s list both studies presented evidence inconsistent with efficient markets looking at newer data and at bond and option prices the authors find that case against market efficiency is not compelling copyright 1991 by university of chicago press

institutional ownership and changes in the s p 500 several recent articles have provided new evidence for the existence of price pressures by examining the price and volume effects associated with changes in the s p 500 the present study extends this work by examining actual changes in institutional holdings following both additions to and deletions from the s p 500 the results show that changes in institutional holdings in response to additions or deletions from the s p 500 are positively correlated in addition to providing further evidence for the existence of price pressure effects the results also provide evidence of the very large institutional elasticities of demand for stock in two recent articles in this journal shleifer 1986 and harris and gurel 1986 present important new evidence of the existence of price pressures by examining the price and volume effects associated with changes in the composition of the standard and poor s s p 500 market index specifically these authors interpret the strong increases in trading volume and economically and statistically significant increases decreases in share prices on the first trading day following additions to or deletions from the s p 500 as the result of increased decreased demand by institutional index funds rather than from information effects concerning the future return distributions of the newly listed delisted firms the results of similar price and volume studies conducted by woolridge and ghosh 1986 and lamoureux and wansley 1987 are also generally consistent with the predictions of the price pressure hypothesis while both schleifer 1986 and harris and gurel 1986 suggest that changes in institutional index fund holdings are responsible for the observed abnormal returns in response to s p 500 changes over the years between 1966 and 1983 their joint failure to examine actual institutional ownership changes following listing or delisting from the index does not allow for direct tests of this possibility this study presents results of such tests

non convexities in continuous time investment theory that non convex preferences or technologies cause problems for economic theory is well known in recent years there have been numerous contributions to the nonconvexity problem in the context of models with a finite dimensional commodity space in the capital theory context non convexities have received explicit treatment in a few papers in two distinguishable ways the problem is cast either in a discrete time framework aoki 1971 rothschild 1971 or in a continuous time framework in which there are implicitly unbounded economies of scale in investment the latter formulation leads to jumps in the state variable or lumpy investment the standard problem treated is one of decreasing costs in the installation of new capacity contributions include chenery 1952 dixit mirrlees and stern 1975 hartwick 1976 manne 1967 srinivasan 1967 starrett 1978 and weitzman 1970 these types of analysis unfortunately ignore some of the most interesting problems associated with non convexities in investment theory in a discrete time framework the important distinction between stocks and flows is blurred while the capacity installation problem by admitting unbounded scale economies excludes the smoothing of state variables that follows by allowing for eventually increasing costs of adjustment in this paper we undertake a systematic examination of non convexities or sometimes non concavities in the context of a classic problem in continuous time investment theory the optimal accumulation of capital by a firm maximizing its present value over an infinite horizon while the results obtained are specific to this particular model we feel that they can be qualitatively extended to any capital theory problem which can be cast in a continuous time optimal control theory framework there are various sorts of non2 convexities which can arise in these problems first there can be either stock or flow non convexities that is non convexities which are introduced into the net benefit function the measure of the flow of benefits at each moment through changes in the capital stock state variable on the one hand or changes in the flow of investment control variable on the other if the benefit and transition functions are not concave in both these variables then necessary conditions are no longer sufficient for optimality and conventional marginal analysis fails non convexities can also be introduced into the value functional which has a stock dimension in order to examine these different sorts of non convexity problems we shall now present the basic economic problem a firm is faced with the problem of maximizing the present value of discounted cash flow over an infinite horizon hence it chooses an investment programme i t to maximize 00

capital gains taxes and equity trading empirical evidence individual investors have an incentive to defer selling appreciated stock until it qualifies for tax favored long term capital gains treatment shackelford and verrecchia 2002 show that these incentives can affect equity trading around public disclosures this article provides some empirical support for their theory with evidence of price increases and equity constrictions around announcements of quarterly earnings and additions to the s p 500 index we find share returns rise and trading volume falls with the incremental taxes saved by deferring the sale of appreciated property the price increases however are temporary reversing in subsequent trading days the results are consistent with buyers believing the compensation to sell before long term qualification through higher prices is less costly than holding an inappropriately weighted portfolio this finding that personal capital gains taxes affect equity trading adds to a growing literature that challenges longstanding assumptions that firm value is independent of shareholders and their taxes

the dartboard column second hand information and price pressure this study analyzes the effect of second hand information on the behavior of security prices and volume using analysts recommendations published in the monthly dartboard column of the wall street journal for the two days following the publication of the recommendations average positive abnormal returns of 4 percent nearly twice the level of abnormal returns documented in previous research on analyst recommendations and average volume double normal volume levels on the two days following publication of the recommendations are documented the positive abnormal return on announcement is partially reversed within 25 trading days the authors conclude that the positive abnormal return on announcement of the recommendations is a result of naive buying pressure as well as the information content of the analysts recommendations

price and volume effects of changes in msci indices nature and causes abstract using changes in the msci standard country indices for 29 countries between 1998 and 2001 we document that stock returns and volumes exhibit index effects in international markets similar to those detected by the studies of us stocks the stocks added to the indices experience a sharp rise in prices after the announcement and a further rise during the period preceding the actual change though part of the gain is lost after the actual change date the stocks that are deleted from the indices on the other hand witness a steady and marked decline in their prices trading volumes increase significantly and remain at high levels after the change date for the added stocks there are also considerable cross country variations in these effects tests using data on various measures reflecting the different hypotheses fail to turn up any evidence in support of information effects our evidence appears to be more supportive of the downward sloping demand curve hypothesis there is some evidence of price pressure and mild evidence of liquidity effect particularly in japan and uk

why are convertible bond announcements associated with increasingly negative issuer stock returns an arbitrage based explanation while convertible offerings announced between 1984 and 1999 induce average abnormal stock returns of 1 69 convertible announcement effects over the period 2000 2008 are more than twice as negative 4 59 we hypothesize that this evolution is attributable to a shift in the convertible bond investor base from long only investors towards convertible arbitrage funds these funds buy convertibles and short the underlying stocks causing downward price pressure consistent with this hypothesis we find that the differences in announcement returns between the traditional investor period 1984 1999 and the arbitrage period 2000 september 2008 disappear when controlling for arbitrage induced short selling associated with a range of hedging strategies post issuance stock returns are also in line with the arbitrage explanation average announcement effects of convertibles issued during the global financial crisis are even more negative 9 12 due to a combination of short selling price pressure and issuer issue and macroeconomic characteristics associated with these offerings

financial asset demand is elastic evidence from new issues of federal home loan bank debt abstract we estimate the slope of the demand curve for newly auctioned fhlb discount notes and investigate the impacts of arbitrage risk and heterogeneity of investor beliefs on demand elasticity our unique dataset of roughly 2900 observations of two price quantity pairs the first from a pre auction dealer survey the second from actual auction results provides the quantity shift necessary to identify demand in contrast to previous findings of downward sloping demand curves for equities we show that demand for newly issued fhlb notes is nearly perfectly elastic during normal market conditions we find however that frictions like arbitrage risk and to a lesser extent heterogeneity of investor beliefs negatively affect elasticity and explain the nearly 50 drop in elasticity observed during the recent financial crisis

s p 500 index additions and earnings expectations stock price increases associated with addition to the s p 500 index have been interpreted as evidence that demand curves for stocks slope downward a key premise underlying this interpretation is that index inclusion provides no new information about companies future prospects we examine this premise by analyzing analysts earnings per share eps forecasts around index inclusion and by comparing postinclusion realized earnings to preinclusion forecasts relative to benchmark companies companies newly added to the index experience signi cant increases in eps forecasts and signi cant improvements in realized earnings these results indicate that s p index inclusion is not an information free event studies that examine the prices of common stocks when they become included in the standard poor s s p 500 index have appeared regularly in leading nance journals since 1986 fascination with the eiect of s p index inclusion on stock prices appears to stem from the possibility that inclusion in the index is an information free eventfinformation free in the sense that s p makes no claim that inclusion represents an endorsement of the newly included stock s future prospects 1 indeed s p makes an a rmative claim to the contrary company

index composition changes and the cost of incumbency abstract this paper provides evidence of information effects and portfolio rebalancing effects that occur when stocks are added to or excluded from the sp however the portfolio rebalancing effects dominate the industry information effects

stock price effects and costs of secondary distributions abstract this study does not support the view that a large number of shares can be sold at the prevailing market price and at a small cost a significant stock price decrease is observed at the initial announcement of secondary distributions the price declines are greater for offerings by officers and directors and for larger offerings but are significant for all types of sellers and for large and small offerings there is no significant price decline at the offering when secondaries are announced in advance underwriting and other selling costs are substantial and are positively related to relative offering size

equipment prices human capital and economic growth abstract this paper presents a multisectoral model of economic growth in which endogenous technological progress is embodied in new equipment capital the difference in the intensity of use of human capital across sectors creates aggregate dynamic non convexities and hence the model may generate multiple balanced growth paths under standard parameter values our model can explain the observed correlations found for a pool of countries between investment rates in equipment capital and income growth on the one hand and between the rate of decline in equipment prices and income growth on the other the model is then used to study the effectiveness of two public policies that have been widely implemented to promote economic growth an equipment investment tax credit and a tax incentive to human capital accumulation our results indicate that both policies have positive effects on equipment investment and on long run growth

price and volume effects associated with changes in the s p 500 list new evidence for the existence of price pressures attempts to identify price pressures caused by large transactions may be inconclusive if the transactions convey new information to the market this problem is addressed in an examination of prices and volume surrounding changes in the composition of the s p 500 since these changes cause some investors to adjust their holdings of the affected securities and since it is unlikely that the changes convey information about the future prospects of these securities they provide an excellent opportunity to study price pressures the results are consistent with the price pressure hypothesis immediately after an addition is announced prices increase by more than 3 percent this increase is nearly fully reversed after 2 weeks the efficient market hypothesis emh predicts that security prices reflect all publicly available information therefore one corollary of the emh is that you can sell or buy large blocks of stock at close to the market price as long as you can convince other investors that you have no private information 1 this statement assumes that securities are near perfect substitutes for each other if so the excess demand for a single security will be very elastic and the sale or purchase of a large number of shares will have no impact on price in contrast to the emh scholes 8 kraus and stoll 5 hess and frost 4 and others propose two hypotheses which predict that a large stock sale purchase will cause the price to decrease increase even if no new information is associated with the transaction the imperfect substitutes hypothesis ish also known as the distribution effect hypothesis assumes that securities are not close substitutes for each other and hence that long term demand is less than perfectly elastic under this hypothesis equilibrium prices change when demand curves shift to eliminate excess demand price reversals are not expected because the new price reflects a new equilibrium distribution of security holders the price pressure hypothesis pph assumes that investors who accommodate demand shifts must be compensated for the transaction costs and portfolio risks that they bear when they agree to immediately buy or sell securities which they otherwise would not trade these passive suppliers of liquidity are attracted by immediate price drops rises associated with large sales purchases they are compensated for their liquidity service when prices rise drop to their fullinformation levels the pph like the emh assumes that long run demand is

price reaction of ethically screened stocks a study of the dow jones islamic market world index this paper investigates the short term effects on the price of the ethically screened stocks of the dow jones islamic market world index djimwi quarterly revisions using a sample of 8 250 stocks from may 1999 through june 2012 we find a significant price reaction of the ethically screened stocks following additions and deletions the results show that additions deletions from emerging stock markets tend to experience a greater and significantly positive negative price response than additions deletions from the developed markets further tests reveal that the price reactions following djimwi revisions are likely to be driven by shifts in investor sentiment rather than changes in firm fundamentals

choice under uncertainty problems solved and unsolved ffifteen years ago the theory of choice under uncertainty could be considered one of the success stories of economic analysis it rested on solid axiomatic foundations it had seen important breakthroughs in the analytics of risk risk aversion and their applications to economic issues and it stood ready to provide the theoretical underpinnings for the newly emerging information revolution in economics 1 today choice under uncertainty is a field in flux the standard theory is being challenged on several grounds from both within and outside economics the nature of these challenges and of our profession s responses to them is the topic of this paper

an analysis of intraday patterns in price clustering on the tokyo stock exchange abstract stock prices tend to cluster at round numbers a phenomenon observed in many markets using tick by tick transaction data this article studies price clustering on the tokyo stock exchange which is a computerized limit order market as for the intraday pattern the degree of price clustering is greatest at the market opening then it decreases during the first half hour and reaches a stable level it does not increase again near the market closing there is no clear difference in clustering between call auctions and continuous auctions

the price response to s p 500 index additions and deletions evidence of asymmetry and a new explanation we study the price effects of changes to the s p 500 index and document an asymmetric price response there is a permanent increase in the price of added firms but no permanent decline for deleted firms these results are at odds with extant explanations of the effects of index changes that imply a symmetric price response to additions and deletions a possible explanation for asymmetric price effects arises from the changes in investor awareness results from our empirical tests support the thesis that changes in investor awareness contribute to the asymmetric price effects of s p 500 index additions and deletions the long held assumption that stocks have perfect substitutes and the perfect elasticity of demand that follows from it is central to modern finance theory if securities have almost perfectly elastic demand then any supply or demand shocks that are devoid of information should have no effect on the prevailing price early empirical research on whether price changes occur in the absence of new information focused on block trades equity issues and stock splits but was unable to exclude information effects around these events since there is no obvious reason to believe ex ante that index changes contain new information they constitute a natural framework for testing whether stocks have almost perfectly elastic or horizontal demand curves a stock s excess return around such changes could be consistent with a downward sloping demand curve with the advent of indexed mutual funds in 1976 and the public announcement of s p index changes in the same year there is much evidence that such announcements are accompanied by an increase in price for firms added to the index if stocks have a short term downward sloping demand curve the price should be momentarily affected by a demand shock due to indexing but that effect

do demand curves for stocks slope down since september 1976 stocks newly included into the standard and poor s 500 index have earned a significant positive abnormal return at the announcement of the inclusion this return does not disappear for at least ten days after the inclusion the returns are positively related to measures of buying by index funds consistent with the hypothesis that demand curves for stocks slope down the returns are not related to s p s bond ratings which is inconsistent with a plausible version of the hypothesis that inclusion is a certification of the quality of the stock

long run implications of investment specific technological change an attempt is made to disentangle its effects from the more traditional hicksneutral form of technological progress the balanced growth path for the model is characterized and calibrated to u s national income and product account nipa data the quantitative analysis suggests that investment specific technological change accounts for the major part of growth jel e13 030 041 047

do demand curves for currencies slope down evidence from the msci global index change traditional portfolio balance theory derives a downward sloping currency demand function from limited international asset substitutability historically this theory enjoyed little empirical support we provide direct evidence by examining the exchange rate effect of a major redefinition of the msci international equity index in 2001 and 2002 the index changes implied large changes in the representation of different countries in the msci world index and therefore produced strong exogenous equity flows by index funds our event study shows a strong announcement effect in which countries with a decreasing equity representation vis a vis the u s depreciated against the dollar

the s p500 index effect reconsidered evidence from overnight and intraday stock price performance and volume abstract this study focuses on s p500 inclusions and deletions examining the impact of potential overnight price adjustment after the announcement of an s p500 index change we find evidence of a significant overnight price change that diminishes the returns available to speculators although there are still profits available from the first day after announcement until a few days after the actual event more importantly observing the tick by tick stock price performance and volume effects on the key days during the event window for the first time we find evidence of consistent trading patterns during trading hours a separate analysis of nasdaq and nyse listed stocks allows for a detailed examination of the price and volume effect at an intra day level we find that index funds appear to cluster their rebalancing activities near to and after the close on the event date suggesting that they are more concerned with tracking error than profit

venture theory a model of decision weights several theories suggest that people replace probabilities by decision weights when evaluating risky outcomes this paper proposes a model called venture theory of how people assess decision weights it is assumed that people first anchor on a stated probability and then adjust this by mentally simulating other possible values the amount of mental simulation is affected by the absolute size of payoffs the extent to which the anchor deviates from the extremes of 0 and 1 and the level of perceived ambiguity concerning the relevant probability the net effect of the adjustment i e up or down vis i vis the anchor reflects the relative weight given in imagination to values above as opposed to below the anchor this in turn is taken to be a function of both individual and situational variables and in particular the sign and size of payoffs cognitive and motivational factors therefore both play important roles in determining decision weights assuming that people evaluate outcomes by a prospect theory value function kahneman and tversky 1979 and are cautious in the face of risk fourteen predictions are derived concerning attitudes toward risk and ambiguity as functions of different levels of payoffs and probabilities the results of three experiments are reported whereas only a subset of the model s predictions can be tested in experiment 1 all fourteen are tested in experiments 2 and 3 using hypothetical and real payoffs respectively several of the model s predictions are not supported in experiment 2 but almost all are validated in experiments 1 and 3 the failures relate to the exact nature of probability payoff interactions in attitudes toward risk and ambiguity for losses the theory and results are discussed in relation to other experimental evidence future tests of the theory alternative models of risky choice and implications of venture theory for explaining further phenomena