[nihilum]

The entire point is that there are intermediate holding periods. Think about intraday speculators and statistical arbitrage funds who trade on scales of minutes to hours. They bridge the gap. Further out you have fundamental hedge funds, individual traders, pension funds, etc.

[paulsutter]

Thanks for the comment - this was the question I most wanted to understand. I realize that durations are on a continuous scale. I personally know people who operate across the full range of durations.

But it's still far from clear to me that grandmothers (aka entrepreneurs) see any liquidity benefit from folks with short holding periods. I'm not saying it's a problem if grandmothers like me dont see a liquidity benefit from HFT. I'm just asking if it exists.