I used to trade institutionally in a previous life. What you can deal at any time depends completely on market conditions at that time. Sometimes tens of thousands of lots are possible in one go and sometimes you can't get a single lot done. Obviously, the bigger, more active and more liquid the market, the easier dealing in size is, but that's just a starting generality, specific conditions at the time of trading is what counts.
It also depends very much on how aggressively you want the trade done. You can usually get a big order done in one go if you are willing to bear large slippage, or you can work it more gently in bits until you get there at very probably a better average price.
Institutional traders who routinely might take on big positions for their market always have to have liquidity as a prime consideration. Something is only worth what you can sell it for. They have to bear in mind how easy or difficult it might be to liquidate a postion and you usually have to wait for demand the other way to be able to let size go without crashing your market. So you are a bit more at the mercy of the market in a big position compared to a small one. Retail traders are spared these problems for the most part, at least one advantadge they have over the big boys!
It also depends very much on how aggressively you want the trade done. You can usually get a big order done in one go if you are willing to bear large slippage, or you can work it more gently in bits until you get there at very probably a better average price.
Institutional traders who routinely might take on big positions for their market always have to have liquidity as a prime consideration. Something is only worth what you can sell it for. They have to bear in mind how easy or difficult it might be to liquidate a postion and you usually have to wait for demand the other way to be able to let size go without crashing your market. So you are a bit more at the mercy of the market in a big position compared to a small one. Retail traders are spared these problems for the most part, at least one advantadge they have over the big boys!
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