probably don't want to work an order
if it is trading 84-85 and have 10k to buy , they may pay up 90 for 10k, with avg of say 87.5.
If mkt is jumpy and they just bid 85 for 10,000, taking 1000 at 85 say, they will move mkt up a few and end up paying more in the end, so it gives them...