Jeremy Grant, who covers exchanges for the Financial Times, said that in racing after high frequency trading the utility functions of exchanges may be lost.

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So for the world as a whole, if a financial transactions tax put a bit of a dampener on financial innovation and trading (whether low frequency or high frequency), that would probably be no reason to weep - unless (to state the obvious) investment banking is your life.

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That could roil the high-frequency trading world, a competitive and controversial business that is transforming the financial markets.

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High frequency trading has been scrutinized in recent years because of its links to financial scares like the Flash Crash.

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But the actual algorithms used to power much of high frequency trading are not well understood, and locked up in hedge funds and large financial firms.

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The SEC still has to deal with all sorts of other issues, mostly to do with high frequency trading and its effects on the markets, along with all the issues it has to tackle with financial reform.

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