Cidara Therapeutics Soars 21% on FDA-Backed Flu Vaccine Acceleration: What's Next for CD388?

Summary
• Cidara Therapeutics (CDTX) surges 21.44% to $89.25, hitting a 52-week high of $90.64
• FDA greenlights accelerated Phase 3 trial for CD388, expanding eligibility to 100M+ U.S. patients
• Single-trial BLA approval pathway and $510.58M cash reserves fuel optimism

Cidara Therapeutics (CDTX) has ignited a 21.44% intraday rally, trading at $89.25 as of 18:19 ET, driven by a regulatory breakthrough. The FDA’s endorsement of an accelerated Phase 3 trial for CD388—a universal flu preventative—has redefined the stock’s trajectory. With a 52-week high of $90.64 and a 20.63% price surge from $73.49, the stock’s volatility and volume (2.5M shares) signal a pivotal inflection point. The expanded trial, targeting 6,000 patients, now includes adults over 65, doubling the U.S. market potential and positioning CD388 as a potential blockbuster.

FDA Greenlight Sparks 21% Surge in Cidara Therapeutics
Cidara’s 21.44% rally stems from the FDA’s approval of an accelerated Phase 3 trial for CD388, a single-dose flu preventative. The agency’s feedback allowed the company to expand the trial population to include adults over 65—doubling the U.S. target from 50M to 100M patients—and fast-track enrollment to begin by September 2025. This regulatory validation, combined with the potential for BLA approval after a single trial, has eliminated prior uncertainties about CD388’s commercial viability. The $510.58M cash reserves post-summer financing further reassure investors, removing near-term liquidity risks and aligning the stock with high-conviction biotech plays.

Biotech Sector Rally: CDTX Outpaces Peers on Flu Vaccine Optimism
The biotech sector saw mixed performance, but CDTX outperformed peers like ABIVAX (ABVX -0.22%) and Nektar Therapeutics (NKTR +1.24%). While ABVX and NKTR traded sideways, CDTX’s 21.44% surge reflected unique catalysts: FDA validation of a novel flu preventative with universal appeal. The expanded trial design, targeting a $100M+ patient pool, differentiates CD388 from competitors’ narrower indications. This regulatory tailwind, coupled with a streamlined BLA pathway, positions CDTX as a sector leader in high-impact infectious disease therapeutics.

Options Playbook: High-Leverage Calls and Volatility-Driven Bets
• 200-day average: $34.42 (far below current price)
• RSI: 67.34 (neutral to overbought)
• MACD: 2.59 (bullish divergence from signal line 1.81)
• Bollinger Bands: Price at $88.655 (above upper band $73.22)

Cidara’s technicals suggest a continuation of the bullish breakout. Key levels to watch include the 52-week high of $90.64 and the 200-day MA at $34.42. The RSI near 67 and MACD divergence indicate momentum is intact, while the Bollinger Bands suggest overextension. For options, focus on high-leverage calls with moderate delta and high gamma to capitalize on short-term volatility.

Top Option 1: CDTX20251017C80 (Call, $80 strike, Oct 17 expiry)
• IV: 77.91% (high volatility)
• Leverage Ratio: 27.67% (moderate)
• Delta: 0.7239 (high sensitivity)
• Theta: -0.2208 (rapid time decay)
• Gamma: 0.0176 (moderate sensitivity to price swings)
• Turnover: $39,163 (liquid)
This call offers 254% price change potential if CDTX breaks $90.64. The high delta and gamma make it ideal for a continuation of the rally, while the 77.91% IV reflects market anticipation of further upside.

Top Option 2: CDTX20251017C90 (Call, $90 strike, Oct 17 expiry)
• IV: 75.60% (high volatility)
• Leverage Ratio: 14.06% (moderate)
• Delta: 0.5109 (moderate sensitivity)
• Theta: -0.2095 (rapid time decay)
• Gamma: 0.0232 (high sensitivity to price swings)
• Turnover: $23,963 (liquid)
This call is a high-gamma play for a breakout above $90.64. The 186% price change potential aligns with the stock’s 52-week high target. The 75.60% IV and 0.0232 gamma suggest strong responsiveness to price surges.

Payoff Estimation: At a 5% upside (target $93.09), the CDTX20251017C80 would yield $13.09 per contract (max profit: $13.09 - $4.94 premium = $8.15). The CDTX20251017C90 would yield $3.09 per contract (max profit: $3.09 - $1.63 premium = $1.46).

Action: Aggressive bulls should prioritize CDTX20251017C80 for a breakout above $90.64. Conservative traders may use CDTX20251017C90 as a high-gamma play if the 52-week high is tested.

Backtest Cidara Therapeutics Stock Performance
Key findings on CDTX after days with ≥21 % intraday jumps (Jan-2022 → 24-Sep-2025)1. Sample size • Only 6 qualifying surge days were detected in the entire period.2. Post-event behaviour (close-to-close, equal-weighted across events) • 1-day median performance: -2.5 % (win-rate 50 %). • Stays negative through day-6, turns positive thereafter. • 10-day: +2.7 %; 20-day: +8.1 %; 30-day: +16.9 %. • None of the horizons pass a simple t-test → results are not statistically significant.3. Best stretch • Largest out-performance versus benchmark occurred on day-23 (+26.6 %), but this is driven by just four winners – low conviction.4. Interpretation • Historical evidence is weak: half the time price reversed lower in the first trading day. • After week-one, upside dominates, yet dispersion is very high; risk of drawdown remains meaningful.5. Practical takeaway • Treat large one-day spikes in CDTX as noise rather than a reliable momentum trigger. • If you do trade the surge, a holding window of 20-25 sessions captured the bulk of historical upside, but size positions modestly.You can inspect the interactive event-study chart (navigate through each day’s distribution, cumulative P&L, and individual event traces) in the module on the right.(If the module does not load, refresh the chat or open the link directly.)

Cidara’s CD388 Trial: A $100M+ Market Catalyst
Cidara’s 21.44% surge is a regulatory and commercial inflection point. The FDA’s endorsement of a single-trial BLA pathway and expanded patient eligibility has redefined CD388’s potential, with a $100M+ U.S. market and global flu season timing. Technicals and options data suggest the rally is far from over, with key levels at $90.64 and $34.42. Investors should monitor the October 17 options expiry for liquidity and volatility clues. Meanwhile, Gilead Sciences (GILD -1.47%) remains the sector leader, but CDTX’s unique catalysts position it as a high-conviction play. Act now: Buy CDTX20251017C80 if $90.64 breaks, or short-term traders can scalp the 52-week high with tight stops.