Frantic trading in VinFast has raised eyebrows, but it's still far from becoming a meme stock. The rally in the Vietnamese electric vehicle maker was once so furious that its market cap briefly surpassed some of the world's largest automakers such as Ford and GM . The stock had gone up almost 700% since it went public via a SPAC in mid-August, briefly touching a whopping $85 billion market capitalization. However, it was easy come, easy go. After a head-scratching six-day winning streak, VinFast has lost 60% this week, cutting its gains since its market debut to about 170%. There…