A popular $3.7 billion oil ETF plunges 20% as crude prices hit historic lows

· *United States Oil Fund shares slipped as much as 20% on Tuesday after a trading halt and continued pressure on the oil market.*
· *The ETF's manager, USCF, said in a regulatory filing it issued the last of USO's registered shares and required SEC approval to create 4 billion more.*
· *The vehicle's connection to oil...