The triangle is one of the most well-known chart patterns in existence. As it relates to Elliott Wave it often precedes a strong final move and gives generally accurate price targets.
An interesting part about the current setup in the Russell 2000 is that at the same time as it is forming a potential triangle it is also forming a H&S patterns. To me, this is great news as the H&S is a lot more obvious than the triangle. That means that one should expect the e wave to take out the trendline in what would also be a broken neck-line. One could assume that such a breakdown would bring a lot of shorts into the fray which would only add to the strength of the next move to the upside as many people would be caught on the wrong side of the trend, which is UP for the entire market. Ideal setup, will continue watching and also begin to look at stocks that make up the index as the theoretical 15% move would include stocks that move a lot more than that.