The Jefferies | TR/J CRB Wildcatters Exploration & Production Equity ETF (WCAT) began trading yesterday (January 20, 2010).  WCAT, the latest ETF from Jefferies Asset Management, provides exposure to small-cap and mid-cap American or Canadian companies that are principally engaged in energy exploration and production. Stocks must have a market capitalization between USD 200 million and USD 2 billion to be eligible for inclusion in the index.  The underlying index has a weighting of 44% in midcap stocks and 56% in small caps.  The country allocation is about 68% US and 32% Canada. The fund currently has 55 holdings with the top 10 being…