I've runa strategy that generated amazing returns over 1999-2008.

 

It literally cut half those returns in 2008-2009, so I tried exporting the data to excel and limitting any value loss to -10 (10% stop loss) and the returns were staggering and nearly double the return over the 12 year period.

 

My Question is:  Is this resasonable (are stop losses actually that effective)?

 

P.S a 5% stop loss is even more effective.