High frequency trading is this, but with very high speeds and lots of competition. This means they have to exert value out of almost infinitesimal price changes.
>As HFT strategies become more widely used, it can be more difficult to deploy them profitably. According to an estimate from Frederi Viens of Purdue University, profits from HFT in the U.S. has been declining from an estimated peak of $5bn in 2009, to about $1.25bn in 2012.
That's 0,007% of U.S. GDP. And probably going down.
>"DEFINITION OF HFT: 1. a strategy which trades for investment horizons of less than one day 2. a strategy which seeks to unwind all positions before the end of each trading day thus HFTs can't deploy large amounts of capital"