This indicator is meant to both show you, and alert you when the market pulls back to various levels. Everything is customizable via the scripts settings. Let me know if you would like anything added.
ps. this was built for use on the weekly candles of an economy-tracking index like SPY, however this will work on any security, and any timeframe.
Levels:
Normal Volatility: 5%
Market Correction: 10%
Market Crash: 20%
Black Swan: 30%