$SPX monthly chart - however honestly forgetting all the other indicators posted below and going with the KISS principle, simply using the standard default setting for Stochastics of 14% K length has been the easiest. Here's a 30 year chart, as far as I can go back on Stocckcharts.com.

The 50% level has been an important level for a long time for Stochastics.

In secular bull markets, such as 1982 - 2000, instead of shorting when %K falls below the 50% level, go flat (because the long term trend is up), and fall below the 50% level tends to be quick spikes only.  

In secular bear markets however (late 2000 - current), the %K stochastic will stay below 50% for much longer periods of time, which is only logical), since Secular Bear markets are typified by long periods (typically 16 - 19 years of sideways up and down movement, vs a secular bull market which lasts the same length of time but increases 10 fold on average from start to finish.

I also added the 11 length RSI indicator at the bottom, I found that going back to 1960 it rarely got oversold on the monthly chart and instead of waiting for the %K to go back above 50% for a long, one could go long early when the RSI closes back over 30%.  I show this via the vertical black lines.  

Red arrows= %K falling below 50%

Green Arrows= %K closing above 50%

Blue arrows indicate support areas being tested such as the 20 month MA or 50% Stochastic 

Black arrows= buy signals from oversold RSI

And again, realize this is a monthly chart, signals come at the end of a month. But honestly how many of you can stomach monthly charts? Many of you have trouble following 15/60 min charts and even daily charts.  A lot of members Steve and I talk to tell us that they are swing traders or long term traders, but then when a position goes against them 5% they can't handle it.  Of course a lot of this has to do with position size, risk tolerance, etc.

I only see this chart as a tool perhaps for long term 401K accounts at jobs that have very restrictive 401K plans that you are not allowed to make changes to (such as once a month or once a quarter) and only offer mutual funds through Fidelity that move with the market and S&P 500.