Gap down indicative of exhaustive price action at the end of a mature bear leg. Sellers were clearly in control of the market. Base / unwinding late 2015 to now [orange trading range], leads to the first close above the 100 EMA since Jul 2014 (3.5 years)- this is very bullish.
Couple this with a weakening dollar, and commodities gaining strength across the board and I think we have a decent long term trade. Play is a bit unique (1) trading w/ ETF (2) trading options against that ETF. This could be a killer idea for 2018 and will likely take a minimum of 2-3 months to get moving before folks start to pile in. This ETF is also lagging the underlying asset it tracks, which I feel is also bullish. In-flows to ETF's by novice traders are at record highs (out of mutual funds).