When I ran a backtest, there was a cliffy drawdown which occurred during the 2013-Jan-06 to 2013-Jan-14. Then i tried to check the 'Daily Positions & Gains' to figure out what happened and found that the loss came from a tumble of a stock, whose symbol is 'STRZ-B'. The price dropped from ~$120 to ~$15 in one day. I felt curious about this so I searched online to check if there occurred a black swan event however I found this...
From google's history chart, you can find the price dropped from $123 to $15 in one week. However, from yahoo's history chart, it seems this stock was never traded at the ~$120 level... During the same period, the price just stayed within the range from $14 to $15 and no split event happened... So what actually happened with this stock?? Thanks.