[nick_dm]

The price has to go up anyway, that's what happens when demand increases, it's nothing to do with HFT. Large block trades like this will often be arrange over the counter (OTC) or on dark pools, so the fund purchasing the shares will get a fixed price and it's up to the market maker to deal with the execution risk in the open market.

Edit: As Harryh said, large mutual fund managers believe that HFT allows them to get better prices for their customers: http://www.cnbc.com/2014/04/25/vanguard-chief-defends-high-f...