The conventional momentum strategy performs poorly overall in China, because stock prices behave very differently when markets are open for trading versus they closed. Stocks that past intraday (overnight) winners persistently outperform those losers the subsequent periods. However, same intraday- (overnight-) suffers dramatically overnight (intraday) Further analysis shows tend to be more (les...

Momentum strategies have historically delivered high Sharpe ratios and large positive alphas. However, returns to these strategies also display significant time-variation that is not very well understood. I show that expected momentum returns vary negatively and monotonically with the formation period return difference between past winners and losers, which I term the momentum gap. A one standa...

This paper proposes a continuous-time heterogeneous agent model of investor behaviour consisting of fundamentalist, contrarian, momentum and market maker strategies to study their impact on market stability and profitability. The underlying stochastic delay integro-differential equation model provides a unified approach to model different time horizons of momentum and contrarian strategies, whi...

We propose a novel measure of the amount of arbitrage capital allocated to the momentum strategy to test whether arbitrageurs can have a destabilizing effect in the stock market. Our measure, which we dub comomentum, aims to capture the extent to which momentum trades by arbitrageurs become crowded. Specifically, we define comomentum as the high-frequency abnormal return correlation among stock...

We explore implications of the rational theory of momentum and reversal in Vayanos and Woolley (2011) for empirical work and portfolio management. We compute closed-form Sharpe ratios of various implementations of momentum and value strategies, of combinations of these strategies, and for general investment horizons. For plausible parameter values, the correlation between momentum and value ret...

In this paper, we analyze momentum strategies that are based on reward-risk stock selection criteria in contrast to ordinary momentum strategies based on a cumulative return criterion. Reward-risk stock selection criteria include the standard Sharpe ratio with variance as a risk measure, and alternative reward-risk ratios with the expected shortfall as a risk measure. We investigate momentum st...