In this one-year daily chart of BIIB, below, we can see that prices have made some sharp moves both up and down -- with gaps in both directions. But let's put that aside and just focus on the past three months. BIIB tested the rising, 200-day moving average line in November and again this month. BIIB rallied sharply in November with the rest of the stock market, but those gains were quickly erased. Bounces in BIIB this month have stopped at the declining, 50-day moving average line.
The On-Balance-Volume line has weakened over the past two months, and the Moving Average Convergence Divergence oscillator is below the zero line. Not a pretty picture. BIIB looks vulnerable to further declines. A close below $280 could precipitate a greater drop. Longs should protect their positions.