 BlackRock MuniYield Investment Fund NYSE:MYFs share price crossed below its 50 day moving average during trading on Thursday . The stock has a 50 day moving average of 13.73 and traded as low as 12.41. BlackRock MuniYield Investment Fund shares last traded at 12.72, with a volume of 22,200 shares trading hands. The businesss 50-day ... 