BOSTON (Reuters) - A number of hedge funds sold positions in two drug companies leading the race to a coronavirus vaccine in the quarter before both announced breakthroughs that lifted their stock prices, while a few took stakes in the companies during that time. Regulatory filings show that hedge funds sold millions of shares in drugmakers Moderna and BioNtech during the third quarter, missing out on big gains this month when each announced their vaccines are more than 94% effective.