70% of Stocks Are Held for Eleven Seconds: Nice Efficient Markets Hypothesis Ya Got There

This is not a market that has any connection to the real world, but a casino–and you are definitely not the house:

As the New York Times dealbook noted in May:

These are short-term bets. Very short. The founder of Tradebot, in Kansas City, Mo., told students in 2008 that his firm typically held stocks for 11 seconds. Tradebot, one of the biggest high-frequency traders around, had not had a losing day in four years, he said.


….The fact that the vast majority of stock market trades are held for 11 seconds shows that the stock market is not a real market with real traders governed by the law of supply and demand, and with no real price discovery.

There is no way the efficient markets hypothesis, in either the weak or strong form, is operating. Eleven second holds can’t be based on information about the quality of the investment because the underlying investment doesn’t fluctuate that rapidly.
Sounds like a good argument for a 0.1% transaction tax.

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6 Responses to 70% of Stocks Are Held for Eleven Seconds: Nice Efficient Markets Hypothesis Ya Got There

  1. Russell says:

    That’s 70% of trades. Not 70% of stocks, nor even 70% of shares traded.

  2. David says:

    we already trim the capital gains tax for holding periods over a year. Just introduce a new, higher capital gains tax rate for holdings less than 1 day.

  3. This doesn’t undermine the idea that asset prices already reflect all publicly available information about the security in question.
    The presence of “noise” in an asset price series due to investor ignorance does, however, undermine this theory to some extent. But it’s worth nothing that the growing prevalence of HFT has an alleviating effect on this ignorance.

  4. mits etram says:

    another idea for another tax on everyone

  5. S. Rega says:

    Everyone? Everyone who trades on the stock market, you mean.

  6. mits etram says:

    @S. Rega: Everyone who has any investment, whether purchasing individual stocks or owning stock through mutual funds. Bid-ask spread will return to about 2% per buy-sell, as it was in 1990, costing multiples more than the tax. 2% reduced annual yield will reduce our retirement by one half over a working lifetime. Compounding is the most powerful force in the universe.

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