Publications and Working Papers for
Mila Getmansky Sherman

Assistant Professor of Finance
  

 

Convertible Bond Arbitrageurs as Suppliers of Capital
with Darwin Choi, Brian Henderson and Heather Tookes

Full paper (pdf)

Abstract: This paper examines the potential impact of capital supply on security issuance.  We focus on the role of convertible bond arbitrageurs as suppliers of capital to issuers of convertible bonds.  We estimate a simultaneous equations model of demand and supply of convertible bond capital, linking the time series of aggregate convertible bond issuance to measures of capital supply:  convertible bond arbitrage hedge fund flows, returns, and a proxy for arbitrageurs' use of leverage.  We find that issuance is positively and significantly related to increases in all three supply measures.  To provide further interpretation, we conduct a second test.  We use the ban on short selling in September and October 2008 as a natural experiment to examine the impact of an exogenous shock to the supply of capital from convertible bond arbitrageurs.  We find a significant decline in issuance during the ban.  Results from both empirical approaches provide evidence that the supply of capital from convertible bond arbitrageurs impacts issuance.

 


Crises and Hedge Fund Risk
with Monica Billio and Loriana Pelizzon

Full paper (pdf)                                                    Supplementary files

Abstract: We study the effects of financial crises on hedge fund risk and show that liquidity, credit, equity market, and volatility are common risk factors during crises for various hedge fund strategies. We also apply a novel methodology to identify the presence of a common latent (idiosyncratic) risk factor exposure across all hedge fund strategies. If the latent risk factor is omitted in risk modeling, the resulting effect of financial crises on hedge fund risk is greatly underestimated. The common latent factor exposure across the whole hedge fund industry was present during the Long-Term Capital Management (LTCM) crisis of 1998 and the 2008 Global financial crisis. Other crises including the subprime mortgage crisis of 2007 affected the whole hedge fund industry only through classical systematic risk factors.

 


Share Restrictions and Investor Flows in the Hedge Fund Industry
with Bill Ding, Bing Liang and Russ Wermers

Full paper (pdf)

Abstract: This paper studies the effect of share restrictions on the flow-performance relation of individual hedge funds.  As such, we reconcile previous research that shows conflicting results for this relation without explicitly considering restrictions.  Specifically, we find that hedge funds exhibit a convex flow-performance relation in the absence of share restrictions (similar to mutual funds), but exhibit a concave relation in the presence of restrictions—our evidence is consistent with both a direct effect of the binding restrictions and an indirect effect that is due to investors endogenizing expected future binding restrictions when investing their money.  Further, we find that live funds exhibit a concave flow-performance relation due to stricter flow restrictions than defunct funds, which display a convex relation.  Finally, we find that money is “smart,” that is, fund flows predict future hedge fund performance; however, this “smart money” effect is eliminated among funds with greater share restrictions.
 


Convertible Bond Arbitrage, Liquidity Externalities and Stock Prices
with Darwin Choi and Heather Tookes, Journal of Financial Economics, Volume 91, Issue 2, February 2009, Pages 227-251.

Full paper (pdf)

Abstract: In the context of convertible bond issuance, we examine the impact of arbitrage activity on underlying equity markets.  In particular, we use changes in equity short interest following convertible bond issuance to identify convertible bond arbitrage activity and analyze its impact on stock market liquidity and prices for the period 1993 to 2006.  There is considerable evidence of arbitrage-induced short selling resulting from issuance.  Moreover, we find strong evidence that this activity is systematically related to liquidity improvements in the stock.  These results are robust to controlling for the potential endogeneity of arbitrage activity.

 


Non-Parametric Analysis of Hedge Fund Returns:  New Insights from High Frequency Data
with Monica Billio and Loriana Pelizzon, Journal of Alternative Investments (forthcoming)

Full paper (pdf)

Abstract: This paper examines four daily hedge fund return indices: MSCI, FTSE, Dow Jones, and HFRX, all based on investable hedge funds, and three monthly hedge fund return indices: CSFB Tremont, CISDM, and HFR, which comprise both investable and non-investable hedge funds. Our study, based on standard statistical analysis, non-parametric analysis of the return distribution, and non-parametric regressions with respect to the S&P 500 index shows that key biases like fund selection, asset liquidity, data frequency, sample period, and index construction methodologies are responsible for different statistical properties of hedge fund indices.  One key variable that highly affects the statistical properties of hedge fund index returns is the “investability” of hedge fund indices. 

 


Systemic Risk and Hedge Funds
with Nicholas Chan, Shane M. Haas and Andrew W. Lo, 2005 (NBER Book Chapter, The Risks of Financial Institutions)

Full paper (pdf)

Abstract:  Systemic risk is commonly used to describe the possibility of a series of correlated defaults among financial institutions---typically banks---that occur over a short period of time, often caused by a single major event. However, since the collapse of Long Term Capital Management in 1998, it has become clear that hedge funds are also involved in systemic risk exposures. The hedge-fund industry has a symbiotic relationship with the banking sector, and many banks now operate proprietary trading units that are organized much like hedge funds. As a result, the risk exposures of the hedge-fund industry may have a material impact on the banking sector, resulting in new sources of systemic risks.  In this paper, we attempt to quantify the potential impact of hedge funds on systemic risk by developing a number of new risk measures for hedge funds and applying them to individual and aggregate hedge-fund returns data. These measures include: illiquidity risk exposure, nonlinear factor models for hedge-fund and banking-sector indexes, logistic regression analysis of hedge-fund liquidation probabilities, and aggregate measures of volatility and distress based on regime-switching models.  Our preliminary findings suggest that the hedge-fund industry may be heading into a challenging period of lower expected returns, and that systemic risk is currently on the rise.

 


What Drives Hedge Fund Returns? Models of Flows, Autocorrelation, Optimal Size, Limits to Arbitrage and Fund Failures
MIT Sloan School of Management Thesis, May 2004

Full paper (pdf)

Abstract: Hedge funds provide an opportunity for investing with few government regulations and high potential returns. Since 1980 this has lead to a dramatic 25% annual increase in the number of hedge funds, with nearly $700 billion managed by hedge funds in 2003. However, high risks associated with hedge fund strategies, competition and limited arbitrage opportunities contributed to an annual attrition rate of 7.10%. In this thesis, models were developed and tested that describe the characteristics of fund returns, fund flows, optimal size and hedge fund life cycles. The TASS hedge fund database provided by the Tremont Company was used for analysis. In Essay One, it was found that hedge fund returns are highly serially correlated compared to the returns of more traditional investment vehicles such as mutual funds. Several sources of such high serial correlation were explored and the research illustrated that the most likely explanation of this derived from asset illiquidity and smoothing of returns. Illiquid securities are not actively traded and market prices are not always available for them. In the case of smoothing, brokers or managers have the flexibility to report partial returns. Consequently, for portfolios of illiquid or smoothed securities, reported returns will tend to be smoother than true economic returns, thereby understating volatility and increasing risk-adjusted performance measures such as the Sharpe ratio. An econometric model of illiquidity exposure was further proposed and estimators for the smoothing profile as well as a smoothing-adjusted Sharpe ratio were developed. Estimated smoothing coefficients were found to vary considerably across hedge-fund style categories and may be a useful proxy for quantifying illiquidity exposure. In Essay Two, the life cycles of hedge funds were analyzed. The findings show that in general, investors chasing individual fund performance decrease the probability of an individual hedge fund liquidating. However, when investors pursue a category of hedge funds that has performed well, the probability of hedge funds liquidating within that category increases because of growing competition among hedge funds; and in such environment, marginal funds are more likely to be liquidated than funds that deliver superior risk-adjusted returns. In the Essay, a model was proposed for calculating an optimal asset size by balancing out the effects of past returns, fund flows, market impact, competition and favorable category positioning.

 


An Econometric Model of Serial Correlation and Illiquidity in Hedge Fund Returns
with Andrew W. Lo and Igor Makarov, 2004 (Journal of Financial Economics, 74 (3), pp.529-610)

Full paper (pdf)

Abstract: The returns to hedge funds and other alternative investments are often highly serially correlated in sharp contrast to the returns of more traditional investment vehicles such as long-only equity portfolios and mutual funds. In this paper, we explore several sources of such serial correlation and show that the most likely explanation is illiquidity exposure, i.e., investments in securities that are not actively traded and for which market prices are not always readily available. For portfolios of illiquid securities, reported returns will tend to be smoother than true economic returns, which will understate volatility and increase risk-adjusted performance measures such as the Sharpe ratio. We propose an econometric model of illiquidity exposure and develop estimators for the smoothing profile as well as a smoothing-adjusted Sharpe ratio. For a sample of 908 hedge funds drawn from the TASS database, we show that our estimated smoothing coefficients vary considerably across hedge-fund style categories and may be a useful proxy for quantifying illiquidity exposure.

 


Sifting Through the Wreckage:  Lessons from Recent Hedge-Fund Liquidations
with Andrew W. Lo and Shauna X. Mei, 2004 (Journal of Investment Management, 2(4), Fourth Quarter, pp.6-38)

Full paper (pdf)

Abstract: We document the empirical properties of a sample of 1,765 funds in the TASS Hedge Fund database from 1994 to 2004 that are no longer active.  The TASS sample shows that attrition rates differ significantly across investment styles, from a low of 5.2% per year on average for convertible arbitrage funds to a high of 14.4% per year on average for managed futures funds.  We relate a number of factors to these attrition rates, including past performance, volatility, and investment style, and also document differences in illiquidity risk between active and liquidated funds.  We conclude with a proposal for the U.S. Securities and Exchange Commission to play a new role in promoting grater transparency and stability in the hedge-fund industry.

 


The Life Cycle of Hedge Funds: Fund Flows, Size and Performance,
2004 (Job Market Paper)

Full paper (pdf)

Abstract: Since the 1980s we have seen a 25% yearly increase in the number of hedge funds, and an annual attrition rate of 7.10% due to liquidation. This paper analyzes the life cycles of hedge funds. Using the TASS database provided by the Tremont Company, it studies industry and fund specific factors that affect the survival probability of hedge funds. The findings show that in general, investors chasing individual fund performance decrease probabilities of hedge funds liquidating. However, if investors follow a category of hedge funds that has performed well, then the probability of hedge funds liquidating in this category increases. We interpret this finding as a result of competition among hedge funds in a category. As competition increases, marginal funds are more likely to be liquidated than funds that deliver superior risk-adjusted returns. We also find that there is a concave relationship between performance and assets under management. The implication of this study is that an optimal asset size can be obtained by balancing out the effects of past returns, fund flows, market impact, competition and favorable category positioning that are modeled in the paper. Hedge funds in illiquid categories are subject to high market impact, have limited investment opportunities, and are more likely to exhibit an optimal size behavior compared to those in more liquid hedge fund categories.

 


Limits to Arbitrage: Understanding How Hedge Funds Fail
with Andrew W. Lo, 2004
 

Abstract: Even if arbitrage opportunities can be found in statistical sense, they might not be exploitable. This paper models such limits to arbitrage in the framework of a hedge fund. In particular, the paper explores how hedge funds fail given arbitrage opportunities. Dynamic relationships between a hedge fund, dealers, a bank, and market are modeled. As a case study, Long Term Capital Management is studied. The model explores a phenomenon that a fund manager who engages in arbitrage and uses high leverage might lose all his money before realizing positions at a profit. As assets go down in value, the firm has to post more collateral. If it is unavailable, this often leads to a hedge fund collapse. However, given that positions are well diversified and not closely correlated, leverage by itself does not lead to collapse of a fund. Correlated positions in the absence of leverage might lead to a loss, but are not subject to collateral collapse. However, the superimposition of both leverage and induced high correlation between assets can lead to collapse. The paper explores these "flight to quality" and "collateral collapse" dynamics.

 


The Dynamics of Global Financial Crises
with Kevin Amonlidviman, Andrew W. Lo, and Rishi Kumar, 2003

Full paper (pdf)

Abstract: This paper presents a Markov chain model of the transmission of financial crises. Using bilateral trade data and a measure of exchange market pressure, a method to determine a set of transition probabilities that describes the crisis transmission dynamics is developed. The dynamics are characterized by one-month conditional crisis probabilities and the probability of a crisis occurring within one year. The framework allows for modeling and comparing various channels of contagion, such as investments and bilateral trade. Using macroeconomic data on 45 countries, the model predicts and gives insights into all of the financial crises that we studied: Mexico (1994), Asia (1997), Russia (1998), Brazil (1999), Turkey (2001), and Argentina (2002).

 


Extrapolation Expectations: An Explanation for Excess Volatility and Overreaction
with Jannette Papastaikoudi, 2002

Abstract: In this paper, we explain excess market volatility by means of momentum and acting on analysts' forecasts. We show excessive price movements with respect to fundamentals can be caused either by "irrational" trend chasing behavior of investors, or by trading too often based on experienced analysts' forecasts (in case of continuous earnings). Price volatility depends on the prevalent investor type and on the type of analysts an investor listens to. Within our market framework, price setting mechanisms are introduced based on demand/supply balance and on trading strategies. In forming their demand, investors consider three factors: their beliefs about the intrinsic value of the marketed assets, past stock performance, and predictions of financial analysts of assets' price targets.

 


Understanding Hedge Fund Failure, 2007

Abstract: This paper studies structural and statistical properties of major hedge fund collapses. Several variables such as investment and accounting strategy, crisis outcome, internal dynamics, fee structure, performance, leverage, asset types, geographical location of investments, transparency, personal characteristics of a hedge fund manager and relationships with brokers are analyzed.