There's very few indicators that can be used as a basis for...

There's very few indicators that can be used as a basis for system trading. By system trading I mean your computer will eg. BUY BHP every time MACD crosses up and SELL BHP every time it crosses down.

ROC 12 (rate of chage over 12 days) is a pretty good meduim term one, especially if smoothed.

Here's what would have happend if you had bought/sold BHP in the example above, with $20 deducted for every trade and $100000 starting capital. This is tested on unseen data (ie. new data). In other words, it's a reliable indicator of future performance.

% return per annum over 2003-present = 19.78%