Chipmaker Ambarella had a strong day Monday with a convincing price bounce off its 50-day moving average. It’s the second time that Ambarella (AMBA), an October 2012 IPO, has found support at the line in its current advance. The first time was in October. The first two bounces off the 50-day line (or 10-week line on a weekly chart) are typically safe places to add to an already successful trade, but it’s riskier after that.