Buying and holding quality growth stocks can be a surefire way to significantly increase your portfolio’s value over the years. Two growth stocks that show lots of promise and are down more than 60% from their 52-week highs are BioNTech SE (NASDAQ: BNTX) and Matterport (NASDAQ: MTTR). Healthcare company BioNTech finished last week at less than $157 per share — down more than 66% from the $464 it peaked at last Aug. 10, which was just after the release of its second-quarter results.