A "true flush" has at least 2 dimensions:
1) an explosive, high volume(capitulatory) drop, and,
2) (usually) a serious test of a significant moving average.
In this case, the sma/ema 200 is the target(was only tested once recently, back in August 2011).
The sma200 comes in at about 18.20, with the ema200 at 18.35.
Though a strong test usually comes with a definite drop below the line(say to 18.00), it also should coinside with a low RSI, OBV, and, Stocastics.
IN August 2011, these hit lows of rsi20, Slow stocastics3, and OBV of -50mil. In this sequence, the lowest we hit was rsi28 and stocastics13, and OBV of -22mil.
The ultimate depth, in this case, is the result of a complex dance between a stronger marketplace fundamental grasp of Ariad's potential, counterbalanced by recognition of increasing capital gains rates,
and fear of the major recession/depression that may precipitate, regardless of whether a "reasonable" resolution of the fiscal cliff ensues.
Obviously, it's not an exact science, but the low to mid 18s looks like a very defensible target, if we get there.
If we don't, as I said, I'll be "very happy" to just hang on to my current position.