110,453 research outputs found
RESTLESS BANDIT MARGINAL PRODUCTIVITY INDICES II: MULTIPROJECT CASE AND SCHEDULING A MULTICLASS MAKE-TO-ORDER/-STOCK M/G/1 QUEUE
No full textThis paper develops a framework based on convex optimization and economic ideas to formulate and solve approximately a rich class of dynamic and stochastic resource allocation problems, fitting in a generic discrete-state multi-project restless bandit problem (RBP). It draws on the single-project framework in the author´s companion paper “Restless bandit marginal productivity indices I: Single-project case and optimal control of a make-to-stock M/G/1 queue”, based on characterization of a project´s marginal productivity index (MPI). Our framework significantly expands the scope of Whittle (1988)´s seminal approach to the RBP. Contributions include: (i) Formulation of a generic multi-project RBP, and algorithmic solution via single-project MPIs of a relaxed problem, giving a lower bound on optimal cost performance; (ii) a heuristic MPI-based hedging point and index policy; (iii) application of the MPI policy and bound to the problem of dynamic scheduling for a multiclass combined MTO/MTS M/G/1 queue with convex backorder and stock holding cost rates, under the LRA criterion; and (iv) results of a computational study on the MPI bound and policy, showing the latter´s near-optimality across the cases investigated.
Pharmaceutical Stock Price Reactions to Price Constraint Threats and Firm-Level R&D Spending
No full textPolitical pressure in the United States is again building to constrain pharmaceutical prices either directly or through legalized reimportation of lower-priced pharmaceuticals from foreign countries. This study uses the Clinton Administration's Health Security Act (HSA) of 1993 as a natural experiment to show how threats of price constraints affect firm-level R&D spending. We link events surrounding the HSA to pharmaceutical company stock price changes and then examine the cross-sectional relation between the stock price changes and subsequent unexpected R&D spending changes. Results show that the HSA had significant negative effects on firm stock prices and R&D spending. Conservatively, the HSA reduced R&D spending by $1.6 billion, even though it never became law. If the HSA had passed, and had many small firms not raised capital just prior to the HSA, the R&D effects could have been much larger.
Determinants of Stock Market Prices in Namibia
No full textThis paper investigates the macroeconomic determinants of stock market prices in Namibia. The investigation was conducted using a VECM econometric methodology and revealed that Namibian stock market prices are chiefly determined by economic activity, interest rates, inflation,money supply and exchange rates. An increase in economic activity and the money supply increases stock market prices, while increases in inflation and interest rates decrease stock prices. The results suggest that equities are not a hedge against inflation in Namibia, and contractionary monetary policy generally depresses stock prices. Increasing economic activity promotes stock market price developmentstock market prices; arbitrage pricing theory; cointegration; impulse reponses; Namibia
Restless bandit marginal productivity indices I: singleproject case and optimal control of a make-to-stock M/G/1 queue
No full textThis paper develops a framework based on convex optimization and economic ideas to formulate and solve by an index policy the problem of optimal dynamic effort allocation to a generic discrete-state restless bandit (i.e. binary-action: work/rest) project, elucidating a host of issues raised by Whittle (1988)Žs seminal work on the topic. Our contributions include: (i) a unifying definition of a projectŽs marginal productivity index (MPI), characterizing optimal policies; (ii) a complete characterization of indexability (existence of the MPI) as satisfaction by the project of the law of diminishing returns (to effort); (iii) sufficient indexability conditions based on partial conservation laws (PCLs), extending previous results of the author from the finite to the countable state case; (iv) application to a semi-Markov project, including a new MPI for a mixed longrun-average (LRA)/ bias criterion, which exists in relevant queueing control models where the index proposed by Whittle (1988) does not; and (v) optimal MPI policies for service-controlled make-to-order (MTO) and make-to-stock (MTS) M/G/1 queues with convex back order and stock holding cost rates, under discounted and LRA criteria
RESTLESS BANDIT MARGINAL PRODUCTIVITY INDICES I: SINGLEPROJECT CASE AND OPTIMAL CONTROL OF A MAKE-TO-STOCK M/G/1 QUEUE
No full textThis paper develops a framework based on convex optimization and economic ideas to formulate and solve by an index policy the problem of optimal dynamic effort allocation to a generic discrete-state restless bandit (i.e. binary-action: work/rest) project, elucidating a host of issues raised by Whittle (1988)´s seminal work on the topic. Our contributions include: (i) a unifying definition of a project´s marginal productivity index (MPI), characterizing optimal policies; (ii) a complete characterization of indexability (existence of the MPI) as satisfaction by the project of the law of diminishing returns (to effort); (iii) sufficient indexability conditions based on partial conservation laws (PCLs), extending previous results of the author from the finite to the countable state case; (iv) application to a semi-Markov project, including a new MPI for a mixed longrun-average (LRA)/ bias criterion, which exists in relevant queueing control models where the index proposed by Whittle (1988) does not; and (v) optimal MPI policies for service-controlled make-to-order (MTO) and make-to-stock (MTS) M/G/1 queues with convex back order and stock holding cost rates, under discounted and LRA criteria.
Stock Market Volatility and Learning
No full textWe study a standard consumption based asset pricing model with rationally investing agents but allow agents' prior beliefs about price and dividend behavior to deviate slightly from rational expectations priors. Learning about stock price behavior then causes the model to become quantitatively consistent with a range of basic asset prizing 'puzzles': stock returns display momentum and mean reversion, asset prices become volatile, the price-dividend ratio displays persistence, long-horizon returns become predictable and a risk premium emerges. Comparing the moments of the model with those in the data using confidence bands from the method of simulated moments, we show that our findings are robust to different assumptions on the system of beliefs and other model features. We depart from previous studies of asset prices under learning in that agents form expectations about future stock prices using past price observations.asset pricing, learning, near-rational price forecasts
Stock returns and foreign investment in Brazil
No full textWe examine the relationship between stock returns and foreign investment in Brazil, and find that the inflows of foreign investment boosted the returns from 1995 to 2005. There was a strong contemporaneous correlation, although not Granger-causality. Foreign investment along with the exchange rate, the influence of the world stock markets, and country risk can explain 73 percent of the changes that occurred in the stock returns over the period. We also find that positive feedback trading played a role, and that the market promptly assimilated new information.stock returns; foreign investment; Brazilian economy
Why are stock market returns correlated with future economic activities?
No full textStock price, because it is a forward-looking variable, forecasts economic activities. An unexpected increase in stock price reflects that (i) future dividend growth is higher and/or (ii) future discount rates are lower than previously anticipated; therefore, the increase predicts higher output and investment. As well, other studies argue for an important relation between the expected stock market return and investment. In this paper, Hui Guo analyzes the relative importance of these mechanisms by using Campbell and Shiller’s (1988) method to decompose stock market return into three parts: expected return, a shock to the expected future return, and a shock to the expected future dividend growth. Contrary to the conventional wisdom, the author finds that dividend shocks are a rather weak predictor for future economic activities. Moreover, the expected return and shocks to the expected future return display different predictive patterns. The results shown here, collectively, explain why the forecasting power of stock market return is rather limited.Stock market
Employee Stock Ownership vs. Profit Sharing
No full textThe idea that profit sharing increases employment has been widely tested, but the theoretical basis for the claim is weak and the empirical results are ambiguous. This paper shows that employee stock ownership based on individually-held stakes avoids the problems of traditional profit sharing. Employee stock ownership shifts employment to the efficient level by either raising employment from an initial state of underemployment or decreasing it from an initial state of overemployment. Since the effect on employment is not unidirectional, empirical tests need to differentiate between traditional profit sharing and employee stock ownership and to condition on the initial state of employment.profit sharing; employee ownership; ESOPs; collective bargaining
Joint Dynamics of Prices and Trading Volume on the Polish Stock Market
No full textThis paper concerns the relationship between stock returns and trading volume. We use daily stock data of the Polish companies included in the WIG20 segment (the twenty most liquid companies quoted on the primary market of the Warsaw Stock Exchange). The sample covers the period from January 1995 to April 2005. We find that there is no empirical support for a relationship between stock return levels and trading volume. On the other hand, our calculations provide evidence for a significant contemporaneous interaction between return volatility and trading volume. Our investigations reveal empirical evidence for the importance of volume data as an indicator of the flow of information into the market. These results are in line with suggestions from the Mixture of Distribution Hypothesis. By means of the Granger causality test, we establish causality from both stock returns and return volatility to trading volume. Our results indicate that series on trading activities have little additional explanatory power for subsequent price changes over that already contained in the price series.abnormal stock returns, return volatility, abnormal trading volume, GARCH-cum-volume, causal relations
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