Instead, it was the Bank of England that decided to intervene in the bond market, offering to buy sovereign debt to stem the plunge in the value of the British pound. The Nasdaq led the way higher, and the best performer there was Biogen, which announced a game-breaking study in its candidate treatment for Alzheimer's. Below, you'll learn why Netflix (NASDAQ: NFLX) and MercadoLibre (NASDAQ: MELI) moved higher Wednesday, along with whether their gains look likely to hold up over the long run.