STRO Bear Put Spread Strategy
STRO (Sutro Biopharma, Inc.), in the Healthcare sector, (Biotechnology industry), listed on NASDAQ.
Sutro Biopharma, Inc. is a clinical-stage biotechnology company focused on the discovery, development, and manufacturing of innovative therapeutic products. Its primary objective is to create protein-based treatments for challenging conditions like cancer and autoimmune disorders. The company achieves this through its proprietary XpressCF+ platform, a unique technology that integrates cell-free protein synthesis with precise, site-specific drug conjugation. Currently, Sutro's pipeline features two lead antibody-drug conjugate (ADC) candidates, both undergoing Phase 1 clinical evaluation. STRO-001 targets the CD74 protein, designed for individuals with multiple myeloma and non-Hodgkin lymphoma. The second candidate, STRO-002, is engineered to bind to folate receptor-alpha, intended for the treatment of ovarian and endometrial cancers.
STRO (Sutro Biopharma, Inc.) trades in the Healthcare sector, specifically Biotechnology, with a market capitalization of approximately $295.3M, a beta of 1.55 versus the broader market, a 52-week range of 6.7-43.85, average daily share volume of 314K, a public-listing history dating back to 2018, approximately 269 full-time employees. These structural characteristics shape how STRO stock options price implied volatility around earnings windows, capital events, and macro-driven sector rotations.
A beta of 1.55 indicates STRO has historically moved more than the broader market, amplifying both the directional payoff and the realized volatility relative to an index-equivalent position.
What is a bear put spread on STRO?
A bear put spread buys an at-the-money put and sells an out-of-the-money put at a lower strike for defined risk and defined reward bounded by the strike width.
Current STRO snapshot
As of June 29, 2026, spot at $32.97, ATM IV 143.80%, IV rank 23.64%, expected move 41.23%. The bear put spread on STRO 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 18-day expiry.
Why this bear put spread structure on STRO specifically: STRO IV at 143.80% is on the cheap side of its 1-year range, which favors premium-buying structures like a STRO bear put spread, with a market-implied 1-standard-deviation move of approximately 41.23% (roughly $13.59 on the underlying). The 18-day window matched to the front-month expiry keeps theta exposure bounded while still capturing the post-snapshot move; longer-dated STRO expiries trade a higher absolute premium for lower per-day decay. Position sizing on STRO should anchor to the underlying notional of $32.97 per share and to the trader's directional view on STRO stock.
STRO bear put spread setup
The STRO bear put spread below is built from the end-of-day chain, with each option leg priced at the bid/ask midpoint of its listed strike. With STRO near $32.97, the first option leg uses a $32.97 strike; additional legs (when the strategy has them) anchor to spot-relative offsets. Premiums come from the bid/ask midpoint on the listed STRO chain at a 18-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 STRO shares for the stock leg in covered calls and collars).
| Action | Type | Strike / Basis | Premium (est) |
|---|---|---|---|
| Buy 1 | Put | $32.97 | N/A |
| Sell 1 | Put | $31.32 | N/A |
STRO bear put spread 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 strike width minus net debit times 100; max loss equals net debit times 100. Breakeven is long-put strike minus net debit.
STRO bear put spread payoff curve
Modeled P&L at expiration across a range of underlying prices for the bear put spread on STRO. 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 bear put spread on STRO
Bear put spreads on STRO reduce the cost of a bearish STRO stock position by selling a lower-strike put; suited to moderate-decline theses where price reaches but does not vastly exceed the short strike.
STRO thesis for this bear put spread
The market-implied 1-standard-deviation range for STRO extends from approximately $19.38 on the downside to $46.56 on the upside. A STRO bear put spread caps both the risk and the reward of a bearish position; relative to an outright long put on STRO, the spread reduces the cost basis but limits the maximum profit to the strike width minus net debit. Current STRO IV rank near 23.64% 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 STRO at 143.80%. As a Healthcare name, STRO options can move on sector-level news flow (peer earnings, regulatory updates, industry-specific macro data) in addition to STRO-specific events.
STRO bear put spread positions are structurally moderately bearish; 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. STRO positions also carry Healthcare sector concentration risk; news flow inside the sector (peer earnings, regulatory shifts, supply-chain headlines) can move STRO alongside the broader basket even when STRO-specific fundamentals are unchanged. Long-premium structures like a bear put spread on STRO are particularly exposed to IV-crush risk through scheduled events (earnings, FDA decisions, central-bank meetings) where IV typically contracts post-event regardless of the directional outcome. Always rebuild the position from current STRO chain quotes before placing a trade.
Frequently asked questions
- What is a bear put spread on STRO?
- A bear put spread on STRO is the bear put spread strategy applied to STRO (stock). The strategy is structurally moderately bearish: A bear put spread buys an at-the-money put and sells an out-of-the-money put at a lower strike for defined risk and defined reward bounded by the strike width. With STRO stock trading near $32.97, the strikes shown on this page are snapped to the nearest listed STRO chain strike and the premiums come straight from the end-of-day bid/ask midpoint.
- How are STRO bear put spread max profit and max loss calculated?
- Max profit equals strike width minus net debit times 100; max loss equals net debit times 100. Breakeven is long-put strike minus net debit. For the STRO bear put spread priced from the end-of-day chain at a 30-day expiry (ATM IV 143.80%), 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 STRO bear put spread?
- The breakeven for the STRO bear put spread 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 STRO market-implied 1-standard-deviation expected move is approximately 41.23%; if the move sits well outside the breakeven distance, the structure's risk-reward becomes correspondingly tighter.
- When should you consider a bear put spread on STRO?
- Bear put spreads on STRO reduce the cost of a bearish STRO stock position by selling a lower-strike put; suited to moderate-decline theses where price reaches but does not vastly exceed the short strike.
- How does current STRO implied volatility affect this bear put spread?
- STRO ATM IV is at 143.80% with IV rank near 23.64%, 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.