Larger funds do cost more to manage. There's a point at which you have to diversify not to mitigate risk but because large buys drive up the cost of the purcha

Larger funds do cost more to manage. There's a point at which you have to diversify not to mitigate risk but because large buys drive up the cost of the purchase. Also, there are a whole bunch of extra SEC rules that kick in when you're changing your position in a stock in which you have a nontrivial percentage of outstanding shares.