I have been using www.stockcharts.com to chart relative strength of a stock compared with $SPX. Is there any service that let you see relative strength of more than one stock against an index at once?
You can do that with stockcharts. Select the "PerfChart" at the bottom... add symbols separated with commas.
I have different approach, easier for me. I look at relative strength during my EOW scans, and refer to daily chart. After other analysis I arrive at my E,S,T's and focus on those stocks for the week. For me personally, I find this method much simpler and less distractive. Happy trading!
There are a couple of systems in this space that enable you to create your own customized index and use it as a filter in addition to the native tickers filter. For example, if you are trading forex and you want to create a "MyFXIndex" comprised of (EURusd+EURJPY+someexoticpair)/3. Once created, you can then create backtests to test your trading thesis against "MyFxIndex" and other filters. So your buy trigger might be: Buy if MyFXINdex> 50 and crossed 50 day Mvg Avg....... My system Amibroker can do that and so can SierraCharts, TradeStation. PM me if you need more deets.