Amgen's Sudden 3% Plunge: What's Behind the Biotech Giant's Intraday Slide?

Summary
• Amgen (AMGN) plunges 3.02% to $278.16, breaking below its 200-day moving average of $287.75
• Intraday range widens to $286.70 high vs. $278.00 low, signaling heightened volatility
• Options chain surges with 158 contracts traded for the October 3rd $275 put, showing bearish positioning

Amgen’s sharp intraday decline has ignited a frenzy in options markets and triggered sector-wide speculation. The stock’s 3.02% drop to $278.16—its lowest since March 2025—coincides with conflicting news on its obesity drug MariTide and a regulatory update on Uplizna. With the healthcare sector mixed and Johnson & Johnson (JNJ) down 0.05%, investors are scrambling to parse signals from technical indicators and options activity.

MariTide's Mixed Results and EMA Approval Spark Volatility
Amgen’s selloff stems from a dual shock: underwhelming investor reaction to MariTide’s Phase 2 obesity trial and muted enthusiasm for the European Medicines Agency’s (EMA) recommendation to expand Uplizna’s indication for IgG4-RD. While MariTide showed 20% weight loss in non-diabetic patients, the crowded obesity drug market—dominated by Novo Nordisk and Eli Lilly—has investors questioning Amgen’s differentiation. Meanwhile, the EMA’s IgG4-RD approval, though positive, lacks immediate revenue potential. The stock’s 3.02% drop reflects a risk-off sentiment as traders price in competitive pressures and regulatory uncertainty.

Bearish Options and ETFs: Navigating AMGN’s Volatile Crossroads
• 200-day average: $287.75 (below current price)
• RSI: 53.7 (neutral but bearish bias)
• MACD: -2.21 (negative momentum)
• Bollinger Bands: Lower band at $271.68 (critical support)

Amgen’s technicals suggest a bearish setup with the 200-day MA acting as resistance and the lower Bollinger band at $271.68 as a key support level. The RSI hovering near 53.7 indicates weakening momentum, while the MACD’s negative divergence confirms downward pressure. For options, two contracts stand out:

• AMGN20251003P275 (Put, $275 strike, Oct 3 expiry):
- IV: 27.16% (moderate)
- LVR: 88.61% (high leverage)
- Delta: -0.3596 (moderate sensitivity)
- Theta: -0.1309 (time decay)
- Gamma: 0.0298 (price sensitivity)
- Turnover: 19,110 (liquid)
- Payoff at 5% downside ($264.25): $10.75 per contract
- This put offers high leverage and liquidity, ideal for capitalizing on a potential break below $275.

• AMGN20251003P277.5 (Put, $277.5 strike, Oct 3 expiry):
- IV: 27.23% (moderate)
- LVR: 66.46% (solid leverage)
- Delta: -0.4372 (strong sensitivity)
- Theta: -0.1202 (time decay)
- Gamma: 0.0313 (price sensitivity)
- Turnover: 150,956 (highly liquid)
- Payoff at 5% downside ($264.25): $13.25 per contract
- This contract’s higher delta and gamma make it a top pick for aggressive bearish bets, given its liquidity and implied volatility.

Action: Aggressive bears should prioritize AMGN20251003P277.5 for a 5% downside scenario. If $271.68 holds, consider a short-term bounce play with the $275 put.

Backtest Amgen Stock Performance
Below is the event-study you requested. Key take-aways are provided first, followed by the interactive report.Main observations• Sample size: 22 trading days on which Amgen (AMGN.O) closed ≥ 3 % lower than the previous day (2022-01-03 to 2025-09-23). • Short-term drift: average next-day return ≈ +0.39 % (win-rate 64 %), but the edge is statistically weak. • Medium horizon: the cumulative average return rises gradually to ≈ +2 % after 30 trading days; significance remains low versus the unconditional series. • Practical implication: a simple “buy-the-dip after a –3 % close” rule has not delivered a reliable excess return on AMGN over the past three years.Automatic parameter choices1. Intraday data were not available, so a –3 % drop was approximated with the daily close-to-close change (pct_chg_close ≤ –3 %). 2. Analysis window: 30 trading days post-event (default for event_backtest_engine). 3. Price series: daily closes. You can refine any of these settings—e.g., use true intraday lows or a different holding window—just let me know.Interactive reportThe module above contains the full day-by-day statistics, cumulative P&L curves and win-rate plots. Feel free to explore it and let me know if you’d like deeper cuts (e.g., shorter holding periods, risk-adjusted metrics, or extending the logic to other tickers).

Amgen at a Crossroads: Watch $271.68 and Sector Sentiment
Amgen’s 3.02% intraday drop reflects a confluence of competitive pressures and regulatory uncertainty. The stock’s technicals—particularly the 200-day MA and Bollinger Bands—suggest a critical test of $271.68 support. Investors should monitor the options chain for liquidity and leverage opportunities, with the October 3rd $275 and $277.5 puts offering high-reward potential. Meanwhile, sector leader Johnson & Johnson’s 0.05% decline underscores broader healthcare sector caution. Act now: Target AMGN20251003P277.5 for a bearish play if $271.68 breaks, and watch JNJ’s performance for sector-wide clues.