Here's a tip for small-time bitcoinica junkies like myself:
You can sell part of your position (assuming it's long) to lower your base price. So if you think a downspike is immanent, you can sell down to a base price that the spike won't affect.
Then after the dust settles, buy back in.
Be careful here. This could confuse people.
Your base price is NOT your zhoutong price
. Did you figure out the formula for that yet?
The base price is price from which your profits / losses are calculated. When going long, a lower base price is preferred; however, this comes only at the trade off of a smaller position. The only way around this trade-off is to increase your position at an opportunity where the BTC price falls below your base price. If you increase your position by buying above your base price, this increases your base price. When you sell above your base price to decrease your position, this decreases your base price. If you sell below your base price, you are taking a loss.
Of course all of the above would be the exact opposite in a short position.
You can decrease your chance of taking loss by selling your position down so that your base price falls below what you think the BTC price might spike down to, however at that point you also lose the profits you would have gained from holding those coins in the case the BTC price spikes up. But, optimally you would just buy those coins back after the downspike.
The formula, as far as I can tell right now, works according to the percentages outlined in the "settings" page.
Here's an example: I am long 90 coins at 5x with a base price of 5.66. Loss tolerance for 5x leverage is 16%. So the price of BTC would have to fall such that my (5x whatever my margin is [i'm not sharing that]) minus (90 * (current BTC price)) would be greater than 16% of my (margin * 5). But if I think the price of BTC will fall soon, I will sell off part of my position to lower my base price.
Profit will be generated if any of those 90 coins are sold above $5.66. Loss only starts when the price of BTC falls below the base price, at which point I would be selling at a loss.
If I were to sell 50 coins right now at about $7, my base price would fall to about $3.98. It seems odd to me that partial liquidation of a position would result in a change of the base price rather than an addition / subtraction to the margin, but then this is my first experience ever with margin trading.
That the base price can be manipulated is a fact though, and if you think there's a spike coming down, I suggest you try to get your base price below it before it happens.
I have edited this post a few times because of general typos. This can be rather complex stuff though, especially when you start adding to / subtracting from your margin while holding a position, and increasing / decreasing your position.