Quote from Hydroblunt:
I'll give you a simple example where it may become apparent that your common sense is lacking.
I go long 800 shares of a stock part of a sector that does 500k-1mil volume a day. It goes my way, I'm in the money and it starts accelerating with a parabolic move. Anyone who trades sector stocks, know that these spikes up get sold into. When they pull back, they pull back hard with little liquidity. And sometimes, they end the move.
Hence I put out an offer out for 200-400 shares at a price that at the moment would need a spike. The rest I plan to hold foreseeing a possible bigger move.
Following your mentality, I would either exit at the spike up with no consideration for the bigger move, hold out for the big move or exit when it's obvious the whole move is over. By scaling, I can capture the spike up with a part of my shares and let the rest ride.
Let's do a simple math example. You are in the money 10 cents and the spike starts. 50% chance the move continues after the spike without knocking you out, 50% chance it won't or just knocks you out. We'll make 10 cent profit the stop, 50 cent the spike, 1 point the "big move".
So scenario A you hold all 800 for the big move (no scaling), scenario B you scale out half at the spike, hold half for the big move. Do the math, it's pretty basic. You can also throw in Scenario C where you exit at the spike with 800 shares, which would show an edge that scaling gives you.
These are all hypothetical numbers, obviously. I think they are somewhat close to reality. And I am ignoring the extra slippage 800 shares would experience.