It harms people who trade frequently. Mutual funds, and more importantly pension schemes, should be trading relatively infrequently. If your pension scheme isn'

It harms people who trade frequently. Mutual funds, and more importantly pension schemes, should be trading relatively infrequently. If your pension scheme isn't taking long term positions you need to find a new scheme as they aren't investing. Proper investing, buying a stock in the belief it will go up massively over the course of many years is trivially affected by HFTs. You may pay less than a penny per share extra on trades, but if you're looking for tens of dollars of capital gain do you care?