A bad seven-month stretch just got worse for Moderna (MRNA -1.96%). The messenger RNA (mRNA) pioneer provided a business and pipeline update at the J.P. Morgan Healthcare Conference on Monday. This update wasn't well-received by investors, and Moderna's share price sank nearly 17%.The conventional investing wisdom is that you shouldn't "try to catch a falling knife." Moderna's stock chart certainly looks like a falling knife. Even before the latest decline, the biotech stock was down roughly 73% since early ...