IMO, this is not a short attack as some would imply, but instead swing traders exiting the stock prior to news. Despite what we want to believe, the news in regards to the COVID19 trials could go either way. Swing traders, who bought in the high $3s or low $4s last week, can make $1 per share at this price and not risk losing money if results are not good. This is the, “sell the news,” approach and it’s common. They are selling now as the data could come as early as Monday, although most of us expect it later next week.