After two ugly sessions, Wall Street finally caught a break. Three completely different catalysts suddenly aligned: A blockbuster biotech surprise A more dovish interpretation of the Fed A major Treasury move that pushed bond yields lower Dow: +0.22%. $S&P 500(.SPX)$ : +0.21%. $NASDAQ(.IXIC)$ Not a huge rally. But the message underneath it is much more interesting: When yields fall, risk appetite can come back very quickly. MODERNA JUST DID SOMETHING ALMOST UNHEARD OF The day's biggest story was $Moderna, Inc.(MRNA)$ . Shares exploded: +177. That's extraordinary. Positive interim Phase 3 results for a cancer vaccine. Moderna became only the second stock in