PRTA Butterfly Strategy
PRTA (Prothena Corporation plc), in the Healthcare sector, (Biotechnology industry), listed on NASDAQ.
Prothena Corporation plc, a late-stage clinical company, focuses on discovery and development of novel therapies for life-threatening diseases in the United States. The company is involved in developing Birtamimab, an investigational humanized antibody that is in Phase III clinical trial for the treatment of AL amyloidosis; Prasinezumab, a humanized monoclonal antibody, which is in Phase IIb clinical trial for the treatment of Parkinson's disease; PRX004 that completed Phase I clinical trial for the treatment of Transthyretin amyloidosis; and PRX005, which is in Phase I clinical trial for the treatment of Alzheimer's disease. Its discovery and preclinical programs include PRX012 for the treatment of Alzheimer's disease; and dual Aß-Tau vaccine for the treatment and prevention of Alzheimer's disease. Prothena Corporation plc has a license, development, and commercialization agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. to develop and commercialize antibodies that target alpha-synuclein; and a collaboration agreement with Bristol-Myers Squibb to develop antibodies. The company was founded in 2012 and is based in Dublin, Ireland.
PRTA (Prothena Corporation plc) trades in the Healthcare sector, specifically Biotechnology, with a market capitalization of approximately $502.6M, a beta of -0.23 versus the broader market, a 52-week range of 4.32-11.8, average daily share volume of 505K, a public-listing history dating back to 2012, approximately 163 full-time employees. These structural characteristics shape how PRTA stock options price implied volatility around earnings windows, capital events, and macro-driven sector rotations.
A beta of -0.23 indicates PRTA has historically moved less than the broader market, dampening realized volatility and producing tighter expected-move bands per unit of dollar exposure.
What is a butterfly on PRTA?
A long call butterfly buys one lower-strike call, sells two ATM calls, and buys one higher-strike call, paying a small net debit for a defined-risk position that maxes out if the underlying pins the middle strike at expiration.
Current PRTA snapshot
As of May 15, 2026, spot at $9.80, ATM IV 81.10%, IV rank 14.28%, expected move 23.25%. The butterfly on PRTA below is built from the same end-of-day chain, with strikes snapped to listed contracts and premiums pulled from the bid/ask midpoint at a 34-day expiry.
Why this butterfly structure on PRTA specifically: PRTA IV at 81.10% is on the cheap side of its 1-year range, which favors premium-buying structures like a PRTA butterfly, with a market-implied 1-standard-deviation move of approximately 23.25% (roughly $2.28 on the underlying). The 34-day window matched to the front-month expiry keeps theta exposure bounded while still capturing the post-snapshot move; longer-dated PRTA expiries trade a higher absolute premium for lower per-day decay. Position sizing on PRTA should anchor to the underlying notional of $9.80 per share and to the trader's directional view on PRTA stock.
PRTA butterfly setup
The PRTA butterfly below is built from the end-of-day chain, with each option leg priced at the bid/ask midpoint of its listed strike. With PRTA near $9.80, the first option leg uses a $9.31 strike; additional legs (when the strategy has them) anchor to spot-relative offsets. Premiums come from the bid/ask midpoint on the listed PRTA chain at a 34-day expiry; the cross-strike IV skew is reflected directly in the per-leg values rather than approximated. Quantity sizing assumes one contract per option leg (or 100 PRTA shares for the stock leg in covered calls and collars).
| Action | Type | Strike / Basis | Premium (est) |
|---|---|---|---|
| Buy 1 | Call | $9.31 | N/A |
| Sell 2 | Call | $9.80 | N/A |
| Buy 1 | Call | $10.29 | N/A |
PRTA butterfly risk and reward
- Net Premium / Debit
- N/A
- Max Profit (per contract)
- Unbounded
- Max Loss (per contract)
- Unbounded
- Breakeven(s)
- None on modeled curve
- Risk / Reward Ratio
- N/A
Max profit equals the wing width minus net debit times 100 (reached when the underlying pins the middle strike); max loss equals the net debit times 100. Two breakevens at lower-wing plus debit and upper-wing minus debit.
PRTA butterfly payoff curve
Modeled P&L at expiration across a range of underlying prices for the butterfly on PRTA. Each row is one sampled price point from the computed payoff curve; the full curve uses 200 price points internally before being summarized into 10 rows here.
When traders use butterfly on PRTA
Butterflies on PRTA are pinning bets - traders use them when they expect PRTA to settle near a specific level at expiration (often the prior close, a round number, or the max-pain strike) and want defined-risk exposure to that outcome.
PRTA thesis for this butterfly
The market-implied 1-standard-deviation range for PRTA extends from approximately $7.52 on the downside to $12.08 on the upside. A PRTA long call butterfly is a pinning play: it pays maximum at the middle strike if PRTA settles there at expiration, with the wing legs capping both the cost and the maximum loss to the net debit. Current PRTA IV rank near 14.28% sits in the lower third of its 1-year distribution, where IV often re-expands toward the mean; this favors premium-buying structures and disadvantages premium-selling structures on PRTA at 81.10%. As a Healthcare name, PRTA options can move on sector-level news flow (peer earnings, regulatory updates, industry-specific macro data) in addition to PRTA-specific events.
PRTA butterfly positions are structurally neutral / pin (limited-risk, limited-reward); the modeled P&L assumes European-style exercise at expiration and ignores early assignment, transaction costs, dividends paid before expiry on the stock leg (when present), and the bid-ask spread on the listed chain. PRTA positions also carry Healthcare sector concentration risk; news flow inside the sector (peer earnings, regulatory shifts, supply-chain headlines) can move PRTA alongside the broader basket even when PRTA-specific fundamentals are unchanged. Always rebuild the position from current PRTA chain quotes before placing a trade.
Frequently asked questions
- What is a butterfly on PRTA?
- A butterfly on PRTA is the butterfly strategy applied to PRTA (stock). The strategy is structurally neutral / pin (limited-risk, limited-reward): A long call butterfly buys one lower-strike call, sells two ATM calls, and buys one higher-strike call, paying a small net debit for a defined-risk position that maxes out if the underlying pins the middle strike at expiration. With PRTA stock trading near $9.80, the strikes shown on this page are snapped to the nearest listed PRTA chain strike and the premiums come straight from the end-of-day bid/ask midpoint.
- How are PRTA butterfly max profit and max loss calculated?
- Max profit equals the wing width minus net debit times 100 (reached when the underlying pins the middle strike); max loss equals the net debit times 100. Two breakevens at lower-wing plus debit and upper-wing minus debit. For the PRTA butterfly priced from the end-of-day chain at a 30-day expiry (ATM IV 81.10%), the computed maximum profit is unbounded per contract and the computed maximum loss is unbounded per contract. Live intraday quotes will differ as the chain moves through the trading session.
- What is the breakeven for a PRTA butterfly?
- The breakeven for the PRTA butterfly priced on this page is no defined breakeven on the modeled curve at expiration, derived from end-of-day chain premiums. Breakeven is the underlying price at which the strategy's P&L crosses zero ignoring transaction costs and assignment risk. The current PRTA market-implied 1-standard-deviation expected move is approximately 23.25%; if the move sits well outside the breakeven distance, the structure's risk-reward becomes correspondingly tighter.
- When should you consider a butterfly on PRTA?
- Butterflies on PRTA are pinning bets - traders use them when they expect PRTA to settle near a specific level at expiration (often the prior close, a round number, or the max-pain strike) and want defined-risk exposure to that outcome.
- How does current PRTA implied volatility affect this butterfly?
- PRTA ATM IV is at 81.10% with IV rank near 14.28%, which is on the low end of its 1-year range. Premium-buying structures (long call, long put, debit spreads) are relatively cheap in this regime; premium-selling structures collect less credit per unit risk.