Decline depth
—
Not currently in the rolling-252-day ≥20% decline universe.
Watch
PRTA
Prothena Corporation plc
5.3σ
decline sigma — volatility-normalized move (typical daily 3.81%)
Current
$9.86
Decline depth
—
Decline σ
5.3σ
TFC
2/5 bearish
Rolling 252-day high
Up day
Down day
Last 90 trading days · data from Alpaca
Structural break signals
PRTA qualifies for the Watch on decline sigma.
Time-frame continuity
2/5 bearish
Latest bar across daily/weekly/monthly/quarterly/yearly time frames. A bar counts as bearish when it's a 2-Down or a red 3.
Decline sigma
5.3σ
Drop from local high over the last 5 bars, expressed in units of the stock's typical daily volatility (3.81% per day).
Past the ≥4σ Watch threshold.
The structural read
What price action says about PRTA.
PRTA qualifies for the Watch on decline sigma — the recent drop measures 5.3σ over a 5-bar window. Sigma scales the move by the stock's own typical daily volatility, so a small percentage drop in a normally-quiet name can land here when the bigger players miss it on a pure-percent threshold.
Upstream TFC read: weak alignment, current phase daily. Last bar types — daily 2U (green), weekly 2D (red), monthly 3 (red).
52-week range
52W low $8.20
46.2% of range
52W high $11.80
Related — same sector
Closest decliners to PRTA
Questions about PRTA
What people ask.
Why is PRTA on Broken Stocks?
PRTA qualifies for the Watch on decline sigma. The recent drop measures 5.3σ over a 5-bar window — large enough that even a small percentage drop is structurally significant given the stock's typical day-to-day volatility (3.81%).
Is PRTA a falling knife?
PRTA is on Broken Stocks for time-frame continuity or decline-sigma reasons rather than headline depth, so the falling-knife label doesn't cleanly apply. The phrase usually requires a meaningful percentage drop from a fresh high. See the structural break signals above for the axis that actually triggered the listing.
Is PRTA a buy?
Broken Stocks does not issue buy or sell recommendations. The list is a rules-based technical warning system. It tracks structural decline depth and recency — not company quality, management, fundamentals, or news. Always do your own research and consult a licensed advisor.
Where is PRTA trading inside its 52-week range?
At $9.86, PRTA sits 46.2% of the way from its 52-week low ($8.20) to its 52-week high ($11.80). A reading below 25% indicates price is hugging the bottom of the range; above 75%, the top.