David Furlonger, an analyst at Gartner, said proprietary algorithms developed by hedge fund and other Wall Street firms are making decisions without human input. "That doesn't necessarily allow for more analytical, reasoned judgment by a human," he said.

Hedge-fund management firms, like , , and are big users of automated trading systems, observers say.

Such firms generally build their own computer infrastructures and design proprietary algorithms that consider the timing, price, and quantity of a trade order, and then initiate the stock buy or sale, all without human intervention.

In 2003, analysts projected that the financial services industry would over two years replacing manual workflows with a new scheme dubbed straight-through processing (STP) of trades.