Hi Karw,
Actually I have a section in my book on variations to the basic system.
One variation is to increase the constant value as the stock value increases. The formula is new CV = (old CV + stock value) / 2.
So, if your constant value is $2,000 and the stock value is at $4,000 at the end of the year, under the basic system you would rebalance back to $2000. Under this variation, you would change constant value to (4000 + 2000)/2 = 3000, and so you would rebalance the position to $3,0000.
I don't use it in my personal trading, because I don't want to track individual constant values, and I don't want a few stocks that rise to start dominating my portfolio (in case they eventually crash or stagnate).
Another variation is an optional stop loss. If the stock falls below 50% (or you could pick another percentage) of your initial purchase, you sell the stock and rebalance into another stock.
