A stochastic differential game of institutional investor speculation

Corporate equities have become increasingly concentrated in the hands of institutional investors. Since these investors trade in large blocks, it is likely that their activities affect equity prices significantly. Knowing this, institutional investors have incentives to manipulate the market. This has transformed the supposedly competitive stock market into a market with imperfect competition and speculation. This paper develops a stochastic differential game to analyze institutional investors speculation. A feedback Nash equilibrium solution is obtained and crucial results (including value functions, investment strategies, and equilibrium price dynamics) are derived in closed-form expressions. In particular, it is shown that the market becomes more volatile with institutional speculation. Institutional investor profits are also shown to vary positively with uncertainty, implying that institutional investment is attracted to highly uncertain markets like emerging markets.