I understand that long and short ETFs which track the S&P MidCap 400 index are good ones for trading MTR signals.  Has any backtesting been done that would reflect the use of 2-beta funds tracking the same index, such as Proshares MVV (200% long) / MZZ (200% short)?  Could it make sense using them?  Thanks.

We ran back-tests using MVV while looking at other ETFs. The returns were not a double return over standard ETFs. We found if an investor wanted double the returns it was a safer bet to buy double the amount of a standard ETF that followed a MidCap 400 index.  The results were posted at one time but we removed it from the site.