Earlier quoted context omitted.
> Something like a minimum holding time is a more reasonable approach. However, there's not a clear cut answer in any case. Why do you want to reduce high frequency trading?
http://www.investopedia.com/articles/markets/012716/four-big... This article has a lot of the reasons. I think loss of confidence in Market Integrity is the most important one.
I'll contest the "confidence in the market" hypothesis, however. As more investors move to index funds, I don't believe "confidence" as defined would have any significant impact by increasing or decreasing, because fewer participants overall will be actively engaged.