NBER Working Papers by Rabih Moussawi

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Working Papers

November 2016Exchange Traded Funds (ETFs)
with Itzhak Ben-David, Francesco Franzoni: w22829
Over two decades, ETFs have become one of the most popular investment vehicle among retail and professional investors due to their low transaction costs and high liquidity, taking market share from traditional investment vehicles such as mutual funds and index futures. Research has shown that in addition to the benefits of enhanced price discovery, ETFs add noise to the market: prices of underlying securities have higher volatility, greater price reversals, and higher correlation with the index. Arbitrage activity is a necessary component in minimizing the price discrepancy between ETFs and the underlying securities. During turbulent market episodes, however, arbitrage is limited and ETF prices diverge from those of the underlying securities.
May 2016The Granular Nature of Large Institutional Investors
with Itzhak Ben-David, Francesco Franzoni, John Sedunov: w22247
Over the last four decades, the concentration of institutional assets in equity markets has increased dramatically. We conjecture that large institutions are granular, that is, they cannot be reduced to a collection of smaller independent entities. Hence, the paper studies whether large institutional ownership has a significant impact on asset prices. We provide evidence of a causal effect of ownership by large institutions on the volatility of their stock holdings. As a potential channel for this effect, we show that large institutions generate higher price impact than smaller institutions. Their trades are larger and concentrated on fewer stocks than those of smaller firms. Moreover, the investor flows to units within the same family are more correlated than the flows to independent enti...
April 2014Do ETFs Increase Volatility?
with Itzhak Ben-David, Francesco Franzoni: w20071
We study whether exchange traded funds (ETFs)--an asset of increasing importance--impact the volatility of their underlying stocks. Using identification strategies based on the mechanical variation in ETF ownership, we present evidence that stocks owned by ETFs exhibit significantly higher intraday and daily volatility. We estimate that an increase of one standard deviation in ETF ownership is associated with an increase of 16% in daily stock volatility. The driving channel appears to be arbitrage activity between ETFs and the underlying stocks. Consistent with this view, the effects are stronger for stocks with lower bid-ask spread and lending fees. Finally, the evidence that ETF ownership increases stock turnover suggests that ETF arbitrage adds a new layer of trading to the underlying s...

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