Factorshares used to have a double whammy ETF that went double leveraged long gold, AND double leveraged short SPX.
It was called FSG.

http://www.businessinsider.com/factorshares-2x-nysefsg-for-only-the-most-hardcore-gold-enthusiast-2011-8?

They pulled it a few years after launching. Not enough hardcores I guess. The gold top didn’t help.
I keep it alive on my system as FSG the second. FSGII. (as UGL/SSO)

I also have alerts telling me when a particular instrument is OS on the monthlies. And another on the weeklies.
When they both show up, its show time.

FSGII has given both of those signals concurrently four times over the last 2yrs: July 15, Dec 15, Oct-Dec 16, and now this week. Solid rallies ensued each time, after a particular trigger signal. So we’re getting closer. To both a GDX bottom and some kind of SPX top (likely w3 of W5 from Feb 16). My sense — late July after opex and as earnings start appearing. Will update as appropriate.