[yummyfajitas]

yes and sophisticated HFT systems screw large funds from moving into and out of positions with relative ease/fairness.

Fact: when you make a large trade, there is a price impact. I.e., if you sell lots of GOOG, the price goes down.

Once upon a time, large funds could use their own sophisticated algorithms to make sure their unsophisticated counterparties feel the price impact. I.e., the big fund disguises their intent, Joe IRA buys from the large fund, and then the price goes down after Joe already owns the stock.

Nowadays, HFT makes the price impact happen immediately, typically splitting the difference with Joe [1].

Why is this worse?

[1] The HFT's try to outbid the large fund in order get ahead of it, resulting in Joe getting a better price.