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The theory of binary evolution predicts that many massive stars should lose their hydrogen-rich envelopes via interaction with a companion -- revealing hot helium stars with masses of $\sim$2--8M$_{\odot}$. However, only one candidate system had been identified, leaving a large discrepancy between theory and observation. Here, we present a new sample of stars -- identified via excess ultraviolet emission -- whose luminosities, colors, and spectral morphologies are consistent with predictions for the missing population. We detect radial velocity variations indicative of binary motion and measure high temperatures ($T_{\rm eff}\sim60-100$kK), high surface gravities ($\log(g)\sim5$) and depleted surface hydrogen mass fractions ($X_{\rm{H,surf}}\lesssim0.3$), which match expectations for stars with initial masses between 8--25 M$_{\odot}$ that have been stripped via binary interaction. These systems fill the helium star mass gap between subdwarfs and Wolf-Rayet stars, and are thought to be of large astrophysical significance as ionizing sources, progenitors of stripped-envelope supernovae and merging double neutron stars., Comment: Original version of manuscript submitted in August 2022, per journal policies. Manuscript passed through referee process and was recommended for publication in Science in March 2023. Conclusions have not changed. Please contact authors for further information. Data and updated manuscript will be made available upon publication. Please also see a companion paper in today's archive posting

In statistics, samples are drawn from a population in a data- generating process (DGP). Standard errors measure the uncer- tainty in sample estimates of population parameters. In sci- ence, evidence is generated to test hypotheses in an evidence- generating process (EGP). We claim that EGP variation across researchers adds uncertainty: non-standard errors. To study them, we let 164 teams test six hypotheses on the same sam- ple. We find that non-standard errors are sizeable, on par with standard errors. Their size (i) co-varies only weakly with team merits, reproducibility, or peer rating, (ii) declines significantly after peer-feedback, and (iii) is underestimated by participants.

Massive stars (~8-25Msun) stripped of their hydrogen-rich envelopes via binary interaction are thought to be the main progenitors for merging neutron stars and stripped-envelope supernovae. We recently presented the discovery of the first set of such stripped stars in a companion paper. Here, we fit the spectra of ten stars with new atmosphere models in order to constrain their stellar properties precisely. We find that the stellar properties align well with the theoretical expectations from binary evolution models for helium-core burning envelope-stripped stars. The fits confirm that the stars have high effective temperatures (Teff~50-100kK), high surface gravities (log g ~5), and hydrogen-poor/helium-rich surfaces (X(H, surf)~0-0.4) while showing for the first time a range of bolometric luminosities (10^3-10^5 Lsun), small radii (~0.5-1Rsun), and low Eddington factors (Gamma_e~0.006-0.4). Using these properties, we derive intermediate current masses (~1-8Msun), which suggest that their progenitors were massive stars (~5-25Msun) and that a subset will reach core-collapse, leaving behind neutron stars or black holes. Using the model fits, we also estimate the emission rates of ionizing photons for these stars, which agree well with previous model expectations. Further, by computing models for a range of mass-loss rates, we find that the stellar winds are weaker than predicted by any existing scheme (Mdot(wind), Accepted for publication in ApJ. Spectral models available via zenodo as described in text. Please also see a companion manuscript detailing the discovery of these systems in today's arXiv posting

We document a robust pattern of beta declining over the age of a firm. We find that changes in systematic risk via firm characteristics and life-cycle stages are insufficient to explain this pattern. Moreover, standard proxies for the quantity and quality of information also explain this pattern only partially. To fully explain this pattern we rely on the increasingly important role of familiarity in financial decision making: familiarity is a determinant of beta and firm age is a proxy for the degree of familiarity that investors feel toward individual stocks. To illustrate the implication of our findings, we document that when we control for firm age there is support for the CAPM and its use as an input for the cost of equity capital calculation.

The article is dedicated to the role of polychrome solutions of the architectonic order in the concept of the Baroque façade. The ancient principles of designing architectural structures, inherited from the Renaissance were subjected to reinterpretations in order to impart different expressive values. The arrangements of façades, initially balanced or even horizontal, were replaced by ambiguous bivalent compositions. Vertical layouts began to dominate in the Baroque. Appropriately selected polychrome of the elements of the order could emphasize the compositional expression. The relationship between the layout of the polychrome in a given architectural order and the expression of a work of art has been established for quite a long time. However, the generally available data on color schemes of architectural structures in baroque buildings are still not fully organized. The paper analyses examples of Baroque façades preserved in their original state and revalorized in recent years after thorough conservator’s research in the field of architecture and color. The examples are mainly designed in the so-called great order, i.e. pertaining largely to church façades. In the Baroque, the vertical direction of the composition was strongly emphasized by multiplying or applying perspective arrangements of supports, and finally by embattled entablatures. The decisive field of change became the shaping of the coloristic decoration of the entablature – decisions regarding the material and color separation of elements of the frieze above the supports. The uniform color of all vertical elements of the façade structure guaranteed an unambiguous verticality of the composition.

Investment managers often manage a portfolio with respect to a benchmark. Typically, they use a mean‐variance optimization framework to maximize the information ratio of their portfolio. We develop an unconventional approach to this question. Given a set of assumptions, we ask what optimal percentage of the benchmark stocks the portfolio manager should select. This optimal portfolio depends on Fisher's and Wallenius's noncentral hypergeometric distributions. We find that the optimal selectivity of a benchmark universe varies from 50% to 80%. These results are provocative, given that many enhanced index portfolio managers select a low percentage of the benchmark universe.

On the example of the Wałbrzych agglomeration housing estates once the most important mining and industrial region in Lower Silesia, this article illustrates the specific significance of the designing of green spaces, including urban layouts, and the issue of protecting unique trees and green spaces in the concepts of estates from the early modernism period after the First World War, in the years 1919-1927. The Wałbrzych housing settlements are crucial due to the fact that they were among the first of their kind, not only in Lower Silesia, but in the whole of the Weimar Republic. The concepts developed during the designing process soon spread beyond the borders of the country. On the basis of literature and source studies it was possible to reconstruct design ideas concerning the composition of green areas in most housing estates in the discussed area. The most interesting were presented, grouped according to the landscape and functional aspects of the use of greenery in housing estates. This made it possible to select specific solutions applied by designers, to indicate sources of inspiration and theoretically developed rules, which both then and now seem to be extremely adequate.

This paper explores the investment impact and performance of a unique group of angel investors, those featured on the television show, Shark Tank. We explore the relationship between their individual characteristics such as their experience, reputation, and network with the performance of their investments. Our findings are counter-intuitive in that we find that many characteristics do not appear to impact performance as measured by survival and website traffic. Furthermore, we found that the Sharks do not have the ability to select outperforming companies on average. However, we found the reputational impact of Shark Tank as a venue is significant.

On March 3, 2017, Professor Stephen A. Ross died unexpectedly. Because of his major contributions to the field of financial economics, many expected that he would be awarded the most prestigious award in economics, the Sveriges Riksbank Prize in Economic Sciences, and were surprised that he had not received the award previously. In this article, the authors summarize the many contributions of Professor Ross and assess their originality, impact, and influence on the field of economics and finance.

We use industry data to investigate how the crowding of an equity space develops due to the portfolio construction process in the equity asset management sector. We find crowding can be reduced by slightly altering the risk management process. We also find that crowding in the financial system could be lower if the distribution of risk model usage amongst portfolio managers was more diversified.

This article discusses the many aspects of organizing and operating a student-managed fund, including the many important educational aspects that allow business students to be more prepared for the real world. The discussion of fund management, trading, and performance is based upon the experiences of the University of San Francisco’s student-managed fund.

The ability of oil investment vehicles to perfectly track spot oil has always been challenging; however, recently many vehicles have underperformed spot oil. We study the behavior of oil futures and exchange-traded products that invest in oil futures to document and understand the source of this tracking error. The primary reason why oil investment vehicles have underperformed spot oil is an increase in contango in oil futures markets that we find might be related to investment crowding and the financialization of commodity markets. We show that from 2006 to 2017, oil futures investing underperformed spot oil and the market was in contango most of the time. Proxies for crowding, such as the concentration of major oil investors and changes in assets under management and fund flows of major oil exchange-traded products, are associated with contango in the futures markets and the divergence between futures and spot returns. We also provide evidence of an impact of the financialization on oil futures prices.

Item does not contain fulltext Rigorous organization and quality control (QC) are necessary to facilitate successful genome-wide association meta-analyses (GWAMAs) of statistics aggregated across multiple genome-wide association studies. This protocol provides guidelines for (i) organizational aspects of GWAMAs, and for (ii) QC at the study file level, the meta-level across studies and the meta-analysis output level. Real-world examples highlight issues experienced and solutions developed by the GIANT Consortium that has conducted meta-analyses including data from 125 studies comprising more than 330,000 individuals. We provide a general protocol for conducting GWAMAs and carrying out QC to minimize errors and to guarantee maximum use of the data. We also include details for the use of a powerful and flexible software package called EasyQC. Precise timings will be greatly influenced by consortium size. For consortia of comparable size to the GIANT Consortium, this protocol takes a minimum of about 10 months to complete.

We use industry data to determine whether crowding of the investment space is caused by portfolio construction processes typical to the investment community. In particular, this paper examines the extent that transaction cost models cause crowding of the investment space, even when the investment models are completely unrelated to one another. We find that as transaction costs become more significant in the portfolio creation process as portfolios increase in size from $500 million to $5 billion, crowding actually declines for long-only portfolios and mainly declines, but sometimes increases for market neutral portfolios. This research sheds more light on how crowding develops through actions by players within the financial system.

This presentation focuses on sources of liquidity and illiquidity in financial markets, price risk and liquidity risk, crowding in financial markets and approaches to modeling crowding.

It has been well documented that oil investing vehicles do a poor job of tracking spot oil over long periods. We create optimized investment vehicles that attempt to use backward- and forward-looking indicators in the oil market in order to better track spot oil. Nevertheless, we find that it is extremely difficult to track spot oil using a combination of oil futures, oil stocks, and oil ETFs. However, some contango drag from investing in oil futures can be eliminated, although at the cost of a higher tracking error, by using a forward-looking dynamic strategy that invests in both oil futures and oil stocks.

Investment managers often manage a portfolio of stocks with respect to a benchmark. Their primary concern is selecting the best stocks to outperform their benchmark, while constraining their tracking error. The most common way of doing this is to use an optimization framework to maximize the information ratio of their portfolio. In this paper, we develop an unconventional approach to determining how a portfolio should be managed with respect to the benchmark. In particular, given some assumptions, we determine what percentage of the benchmark stocks would be optimal for the portfolio manager to select. The optimal portfolio depends on Fisher’s noncentral hypergeometric distribution and the Wallenius noncentral hypergeometric distribution. We find that the optimal selectivity of a benchmark universe varies from 50% to 80%, when managers have selection ability. The information ratio and the selectivity percentage can vary as the selection ability of the portfolio manager changes and as the underlying size of the universe changes. These results are provocative, given that many enhanced index portfolio managers select a low a percentage of the benchmark universe.

Investment products that seek to provide leveraged and inverse exposure to the equity markets have enjoyed great success in attracting assets. The largest and most popular exchange traded funds (ETFs) that provide these exposures rebalance their positions each day in an attempt to provide a precise multiple of the market return for the subsequent day. However, the daily rebalancing process can be detrimental to returns over holding periods longer than one day. For investors looking for leveraged or inverse exposure for holding periods greater than one day, a less frequent rebalancing cycle may be more appropriate. Further, moving away from a straight market-capitalization-based weighting methodology may offer opportunities to enhance the return profile thereby enabling an investor to better achieve her long-run investment objectives.

In the last 20 years, the amount of assets managed by quantitative and qualitative hedge funds have grown dramatically. We examine the difference between quantitative and qualitative hedge funds in a variety of ways, including management differences and performance differences. We find that both quantitative and qualitative hedge funds have positive risk-adjusted returns. We also find that overall, quantitative hedge funds as a group have higher αs than qualitative hedge funds. The outperformance might be as high as 72 bps per year when considering all risk factors. We also suggest that this additional performance may be due to better timing ability.

The international sports betting markets are becoming more global, but there is still a large concentration of local bettors in gambling markets of individual countries. Home loyalty and other patterns of human behavior might lead to odds for international competitions being different in different countries with less favorable odds being quoted in the home country; the home bias effect. In this paper we explain the logic of this phenomena and examine a small data set to show the existence of the bias in three different sports: tennis, golf, and European football. We also suggest ideas for a more thorough investigation of the home bias phenomenon.

We use industry data to determine whether crowding of the investment space is caused by portfolio construction processes typical to the investment community. In particular, this paper examines the extent that transaction cost models cause crowding of the investment space, even when the investment models are completely unrelated to one another. We find that as transaction costs become more significant in the portfolio creation process as portfolios increase in size from \$500 million to \$5 billion, crowding actually declines for long-only portfolios and mainly declines, but sometimes increases for market neutral portfolios. This research sheds more light on how crowding develops through actions by players within the financial system

The literature shows that beta is time-varying and difficult to predict using historically measured beta. We postulate that beta has an uncertainty component reflecting the life-cycle of the firm. Young firms are typically untested entities with considerable uncertainty. As this uncertainty resolves itself, the firm's beta declines. We document this decline and provide evidence that firm age is an important determinant. Fundamental factors and non-age proxies for information and uncertainty only partially explain this pattern. Overall, age is an important conditioning variable to consider when examining the time-variation of beta and the relation between beta and cost of capital.

The price of oil has fluctuated wildly in the last few years and has placed a spotlight on oil investing vehicles. Of particular interest has been the discrepancy between oil investing returns and the hypothetical returns to spot oil. We attempt to understand the source of that discrepancy by examining the behavior of oil investing returns over the last 20 years. We find that spot oil is not a realistic investable benchmark for oil investing and propose a better benchmark for oil investing that takes into account storage and insurance costs. Asset allocation studies that use spot oil are flawed and will give oil more importance than it should have relative to other commodities and other asset classes. We also find different strategies of rolling oil futures can have very different return and risk characteristics. The futures curve has transitioned over the last 20 years from backwardation to contango leading to a drag on oil investing relative to prior periods when backwardation was the norm and investors could benefit from the futures roll.We compare different oil investment vehicles and find that investment vehicles that purchase direct stakes in oil companies avoid the contango drag, but do not track oil well and assume other unwanted risks for oil investors. The greatest exposure to oil is achieved by investment vehicles that buy oil futures.

The objective of Bruno and Chincarini is to explore and identify the inflation embedded in a broad range of asset classes beyond simplyTIPS, oil, gold, and real estate. Their analysis is conducted from the perspective of a U.S. investor. The authors find that an investor who is looking for a positive real return of 4.5% while minimizing the downside with respect to inflation will have an allocation that consists primarily of short-term bonds, longer-term bonds, some gold, some oil, and some emerging market equities. The weight of gold and oil together is less than 10% of the portfolio. Bruno and Chincarini also find that TIPS are only slightly effective for protecting against inflation, conditional on an investor using a group of asset classes. The out-of-sample performance of the real return optimizations is quite promising, providing an emulative inflation-protection strategy for U.S. investors.

The objective of this paper is to explore and identify inflation as it is embedded in a broad range of asset classes beyond simply TIPS, oil, gold and real estate. The analysis is conducted primarily from the perspective of investors in a range of countries that span the developed and emerging world including resource intense economies and those that have previously experienced hyperinflation. We find that an investor who is looking for a reasonable positive real return of 4.5% while minimizing the downside risk with respect to inflation will have an allocation that consists primarily of short-term bonds, longer-term bonds, some gold, some oil, and some emerging market equities. The weight of gold and oil together is less than 10% of the portfolio and is not always relevant for all countries. We find that achieving stable real returns during hyperinflationary periods is virtually impossible without access to a vast array of short-term fixed income instruments. Despite this, the out-of-sample performance of the real return optimizations is quite promising, providing an emulative inflation protection strategy for international investors of all sorts.

This article examines the efficiency of a relatively new market, the weather derivatives market. The weather market is an especially interesting market to study, since it is relatively new and less liquid and whose underlying has no fundamental value. We examine the weather derivatives futures market traded on the CME (Chicago Mercantile Exchange) in both HDD (heating degree days) futures contracts and CDD (cooling degree days) futures contracts in 18 cities across the United States. We examine the efficiency of the weather market in three ways. The first way is by comparing the market's implied forecasts for the weather against other forecasts, including variations of a historical forecasts and forecasts based upon the National Weather Service 7-day MOS prediction model. The second way is by looking at surprise temperatures across cities and across different days of the month and subsequent returns from buying or selling those weather futures contracts. We examine the properties of these returns to determine whether we observe overreaction in the weather derivatives market. The third way is by looking at weather patterns across different cities, i.e. cross auto-correlation of actual weather patterns compared to derivative contracts. In this article, we find that the weather derivatives market is quite efficient despite its lack of depth. It also might indicate that markets with shorter horizons and an impossibility of inside information will generally be more efficient.

The speculative activities of hedge funds have generated considerable interest among market agents and regulatory institutions. In September 2006, the activities of Amaranth Advisors, a large-sized Connecticut hedge fund in the natural gas market resulted in serious losses. By September 21, 2006, Amaranth had lost roughly $4.35B over a 3-week period or one half of its assets due to its activities in natural gas futures and options in September. Shortly thereafter, Amaranth fund was liquidated. This article presents a brief investigation of the possible causes behind this spectacular hedge fund failure and draws lessons by assessing Amaranth9s trading activities within a standard risk management framework. Even by conservative measures, Amaranth was engaging in highly risky trades which in addition to high levels of market risk involved significant exposure to liquidity risk—a risk factor that is seemingly difficult to manage.

Chincarini and Kim (2006) argued that the information ratio can be interpreted as the square root of $R^{2}$. In this paper, we further develop this argument by, first, making a distinction between the conditional and the unconditional information ratio and, then by clarifying the relationship between $R^{2}$ and two versions of the information ratio. This paper also discusses the implications of our approach for interpreting the Fundamental Law of Active Management.

Global equity portfolio managers employ a variety of approaches to currency hedging either hedging all of their currency risk, hedging only a portion of their currency risk, or simply not hedging at all. This paper considers a hypothetical US-based global portfolio invested in Europe, Asia, Latin America, and the US and looks at how various passive hedging strategies would have performed over the post-Asian crisis period from 1999 to 2006, while also looking at individual currency hedges in isolation over a longer time period (from 1984 to 2006). Although it is well known that currency hedging reduces the volatility of dollar returns, some recent studies have argued that hedging is less important in emerging markets due to the negative correlation between currency returns and local equity returns. The Sharpe ratio of this hypothetical global portfolio is examined to determine which currency hedging approach did the best on a risk-adjusted basis from 1999 to 2006. Five hypothetical global portfolios are considered. The benchmark portfolio is market-capitalisation weighted, while the others are more European weighted, equal weighted among regions of the world, and with large investments in emerging markets, like Asia and Latin America. As in other studies, it is found that currency hedging reduces portfolio risk and improves the performance of most portfolios on a risk-adjusted basis for managers with exposures to single foreign countries. For global investment managers with exposure to many countries and using simple, yet very common hedging techniques, currency hedging did not improve the risk-adjusted returns of the portfolio in most cases compared to a policy of no currency hedging. This was primarily due to the consistent depreciation of the US dollar versus most currencies in the world during this period of time. Even though it did not improve the risk-adjusted returns of the portfolio, currency hedging reduced the overall volatility of the portfolio marginally compared to the unhedged case. As expected, the hedging return volatility matched more closely with the local equity return volatility. The only global portfolio for which hedging improved the risk-adjusted returns was for the global portfolio that was heavily invested in South American equities. The results of this paper also indicate that using a hedging strategy that employs only three optimally weighted currencies performed equally well when compared with a strategy using all currencies to hedge the global portfolio.