A Wall Street firm just downgraded Netflix, and now the stock is tumbling (NFLX)

Wikimedia Commons Netflix has made itself into a fixture in the entertainment business. But according to one Wall Street firm, the company's days of booming growth may be over. William Power and Steven Beckert at Baird downgraded Netflix to "Neutral" from "Buy" in a note Monday, saying the company's subscriber count may have plateaued. "In our Q4 U.S. survey, 46% of respondents stated that they were Netflix streaming subscribers vs. 47% in Q3 and 35% a year ago," Power and Beckert wrote. "This a...