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Amgen Inc. (NASDAQ:AMGN) shed roughly $12 billion in market value after hours on September 4, 2026. The stock declined by about 5% to $415. The reason, as strange as it sounds, is a drug it does not own. Novartis announced that pelacarsen, an Lp(a)-lowering therapy, missed its Phase 3 cardiovascular-outcomes trial, Lp(a)HORIZON. And since Amgen's late-stage asset olpasiran relies on the same biological premise, investors immediately marked down Amgen on the negative read-through.
The result strikes at a premise rather than at a product. Pelacarsenhad lowered Lp(a) by roughly 80% in earlier studies. In Lp(a)HORIZON, Novartis said pelacarsen substantially lowered Lp(a), but it still failed to reduce the composite of cardiovascular death, heart attack, stroke, and urgent revascularization. It still could not reduce the composite of cardiovascular death, heart attack, stroke, and urgent revascularization. And now the entire hypothesis that lowering Lp(a), a genetic cardiovascular risk factor, actually cuts events, is being directly challenged. Olpasiran is built on the same hypothesis, leading to the repricing of odds as soon as pelacarsen's data were out.
Amgen's olpasiran, an siRNA, lowered Lp(a) by more than 95% at certain doses in Phase 2, compared with reductions of roughly 80% for pelacarsen in earlier studies. The bull case is that this deeper reduction could help olpasiran deliver better cardiovascular outcomes.. The bull case is that this 15% will help Amgen to make a deeper cut and deliver results. While biologically possible, the Lp(a)HORIZON trial provided no evidence that a clinical threshold exists above an 80% reduction. The topline Phase 3 announcement did not establish that deeper Lp(a) lowering would have produced a cardiovascular benefit. It is therefore appropriate to say that the miss lowered olpasiran's probability of success rather than pretending it is irrelevant. Eli Lilly's lepodisiran is running the same deep-reduction experiment, so the hypothesis will be tested with or without Amgen.
Amgen is not an Lp(a) pure-play. MariTide in obesity, Repatha in cholesterol, and Tezspire in asthma drive more value for the company, and this diversification creates a cushion for the stock, although the selloff ultimately became much larger than the initial 5% after-hours reaction. Positioning has stayed calm since the beginning of 2026. Insider Monkey data shows 66 hedge funds held AMGN in the second quarter of 2026, up slightly from 65 in the first. Short interest, on the other hand, sits at just 2.4% of float, reflecting minimal bets against the stock in the market.
The 5% fall marks a setback rather than a dip-buying opportunity. The success rate of olpasiran is questioned, and the deeper-cut argument with a 15% difference is only a hypothesis that has neither been proved nor disproved. But as a diversified large-cap biotech where other assets drive substantial value, Amgen's valuation depends on far more than olpasiran. Consider Amgen Inc. (NASDAQ:AMGN) for its broad drug portfolio and defensive market profile. Do not make the decision based on olpasiran alone. Olpasiran's own cardiovascular outcomes readout will provide the final verdict, but near-term performance will be determined by clinical progress from MariTide.
While we acknowledge the potential of AMGN as an investment, we believe certain AI stocks offer greater upside potential and carry less downside risk. If you're looking for an extremely undervalued AI stock that also stands to benefit significantly from Trump-era tariffs and the onshoring trend, see our free report on the best short-term AI stock.
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Amgen Shares Fall as Novartis' Pelacarsen Misses Phase III Study Goal Zacks • 5d ago AMGN NVS
Amgen Shares Fall as Novartis' Pelacarsen Misses Phase III Study Goal
Amgen's 7,297-Patient Heart Bet Just Inherited a Higher Bar GuruFocus.com • 5d ago AMGN NVS
Amgen's 7,297-Patient Heart Bet Just Inherited a Higher Bar
Amgen Drops 10% on a Trial It Didn't Even Run MarketBeat • 1d ago AMGN NVS
Amgen Drops 10% on a Trial It Didn't Even Run
Amgen Stock Suffers Worst Day in More Than Two Decades The Wall Street Journal • 4d ago AMGN NVS
Amgen Stock Suffers Worst Day in More Than Two Decades
Amgen Shares Fall as Investors Assess Novartis Lp(a) Trial Result and BMO Downgrade InvestorsHub • 5d ago AMGN NVS
Amgen Shares Fall as Investors Assess Novartis Lp(a) Trial Result and BMO Downgrade
Jim Cramer Weighs Amgen (AMGN) After Novartis Trial Failure Insider Monkey • 1d ago AMGN NVS
Jim Cramer Weighs Amgen (AMGN) After Novartis Trial Failure
Amgen Falls 10% as Novartis Trial Failure Clouds a Cholesterol Drug Class; NVS Stock Drops 14% 24/7 Wall St. • 4d ago AMGN LLY
Amgen Falls 10% as Novartis Trial Failure Clouds a Cholesterol Drug Class; NVS Stock Drops 14%
Why Novartis’ Drug Trial Results Are Blowing Up Amgen Stock Barrons.com • 5d ago AMGN NVS
Why Novartis’ Drug Trial Results Are Blowing Up Amgen Stock
Amgen's Olpasiran May Still Show Heart-Risk Reduction Despite Novartis Miss, UBS Says PREMIUM MT Newswires • 4d ago AMGN NVS
Amgen's Olpasiran May Still Show Heart-Risk Reduction Despite Novartis Miss, UBS Says
NVS, IONS, AMGN Stocks Drop After-Hours — What’s Driving The Selloff? Stocktwits • 8d ago IONS NVS
NVS, IONS, AMGN Stocks Drop After-Hours — What’s Driving The Selloff?
