Insmed Stock (INSM) Rebounds on Dec. 19, 2025 After BiRCh Trial Miss: Latest News, Analyst Forecasts, and What Comes Next

December 19, 2025 — Insmed Incorporated (NASDAQ: INSM) is back in focus today after a sharp, news-driven selloff on Thursday and a noticeable bounce on Friday. As of 15:46 UTC on Dec. 19, INSM shares were trading around $174.90, up roughly $8.35 (+5.0%) versus the prior close, with the day’s range spanning about $166.01 to $174.90.

That rebound follows a steep Thursday decline after Insmed reported that its Phase 2b BiRCh trial of brensocatib (brand: Brinsupri) in chronic rhinosinusitis without nasal polyps (CRSsNP) missed endpoints, leading the company to discontinue development in that indication. ^[1]

What’s driving the stock today isn’t just the trial update—it’s the rapid wave of sell-side reassessments and fresh coverage initiations published on Dec. 19, 2025, including a reiterated Buy call from Goldman Sachs and a Buy initiation from Truist, both emphasizing that the company’s long-term story still hinges on its bronchiectasis franchise and broader respiratory pipeline. ^[2]

INSM stock price action today: volatility, then a bounce

Insmed’s shares have been moving fast this week:

Thursday (Dec. 18): INSM closed at $166.55, down 16.08%, with volume surging to about 13.49 million shares (far above typical daily trading). ^[3]
Friday (Dec. 19): the stock recovered into the $170s, with lighter (but still elevated) volume relative to Thursday’s capitulation-like session. ^[4]

Even after Friday’s rebound, INSM remains well below its 52-week high of $212.75.

What happened: Insmed’s BiRCh CRSsNP trial missed—and the program was dropped

The core catalyst behind this week’s volatility is Insmed’s announcement of topline results from the Phase 2b BiRCh study evaluating brensocatib in CRSsNP.

Key trial details and results reported by the company:

Design: randomized, double-blind, placebo-controlled, multicenter Phase 2b trial. ^[5]
Scale:288 patients enrolled across 104 sites globally, randomized 1:1:1 to brensocatib 10 mg, brensocatib 40 mg, or placebo for 24 weeks. ^[6]
Background therapy: all participants continued daily mometasone furoate nasal spray. ^[7]
Efficacy: improvements were not meaningfully better than placebo. At 24 weeks, patients’ Sinus Total Symptom Score (sTSS) decreased by about 2.2 points (10 mg) and 2.33 points (40 mg), while the placebo arm declined 2.44 points. ^[8]
Safety: the company stated the drug was generally safe, with no new safety signals. ^[9]

Insmed said it would discontinue developing brensocatib for CRSsNP following the miss. ^[10]

Why did it miss?

A key theme in today’s commentary is placebo performance. BioSpace reports that Insmed pointed to a strong placebo response as a major factor behind the failure, and Guggenheim analysts highlighted that placebo patients performed far better than expected after discussions with management. ^[11]

This matters because it frames the result less as “the mechanism doesn’t work” and more as “this particular trial environment didn’t separate drug effect from placebo/background-therapy effects”—an important nuance for how investors model the remaining brensocatib opportunity.

Today’s new development: Insmed adds INS1148 to the pipeline

Alongside the BiRCh update, Insmed also announced the acquisition of INS1148, described as an investigational monoclonal antibody with potential in respiratory, immunological, and inflammatory diseases. The company said it plans to advance INS1148 into Phase 2 studies initially in interstitial lung disease and moderate-to-severe asthma. ^[12]

Importantly, the company did not disclose financial terms of the deal in the reporting accessible today. ^[13]

From a stock narrative perspective, the timing is not accidental: this acquisition gives investors something additive to discuss, even as the market reprices one portion of brensocatib’s expansion optionality.

Dec. 19 analyst coverage: Goldman reiterates Buy; Truist initiates with Buy

Goldman Sachs: Buy reiterated, $225 target (published Dec. 19)

In a note published this morning, Investing.com reports that Goldman Sachs reiterated a Buy rating and kept a $225 price target after meeting with Insmed’s management team (including CEO Will Lewis and CFO Sara Bonstein). ^[14]

Notable takeaways from the Goldman view:

Management discussed reasons behind the BiRCh failure, but Goldman maintained a constructive stance on the broader story. ^[15]
Goldman highlighted continued confidence in DPP-1 inhibition in other neutrophil-mediated diseases (citing interest in areas such as rheumatoid arthritis and inflammatory bowel disease) and referenced a follow-on compound INS1033 expected to enter clinical trials in 2026. ^[16]
The firm emphasized the need for 1–2 full quarters to better judge the Brinsupri launch trajectory in bronchiectasis, while noting early adoption signals were encouraging. ^[17]

Goldman’s framing is effectively: CRSsNP was upside, not the foundation—and the foundation (commercial bronchiectasis + pipeline) remains intact.

Truist Securities: Coverage assumed with Buy, $205 target (published Dec. 19)

In another Dec. 19 publication, Investing.com reports that Truist assumed coverage on Insmed with a Buy rating and a $205 price target. ^[18]

What stands out in the Truist thesis:

Truist calls the post-trial selloff a “valuation reset” that creates an opportunity to buy ahead of what it describes as the anticipated Brinsupri bronchiectasis launch ramp. ^[19]
Truist cites a doctor survey indicating potential for broad adoption: physicians expected about 35% of their bronchiectasis patients to start within 12 months, with penetration rising to 73% over five years. ^[20]
Truist placed its $205 target within a broader analyst range of $158–$263, as reported by Investing.com. ^[21]

Important context: Brinsupri is already FDA-approved in the U.S. for non-CF bronchiectasis, according to Reuters reporting earlier this week, so “launch” language in analyst notes may reflect expectations for expansion, international ramp, or broader uptake rather than initial approval. ^[22]

BioSpace analysis today: “rare disappointment,” but Guggenheim still sees a large core opportunity

A BioSpace piece published December 19, 2025 captures the tone from at least one key bull camp: Guggenheim called the CRSsNP miss a “rare disappointment,” but projected the impact would be limited given the size of the core bronchiectasis commercial opportunity. ^[23]

BioSpace also reports that Guggenheim continues to see ~$9 billion in peak sales potential for Brinsupri in non-cystic fibrosis bronchiectasis (NCFB) alone—an aggressive forecast, but notable as a signal of where bullish modeling still sits after the setback. ^[24]

The same piece flags enthusiasm around Insmed’s TPIP program (treprostinil palmitil inhalation powder), noting prior Phase 2b performance and expectations for Phase 3 timing discussed by the company in prior communications. ^[25]

Market forecasts: where Wall Street price targets stand on Dec. 19, 2025

If you’re trying to translate all the headlines into a practical “forecast,” the cleanest public metric is the street price-target cluster.

Consensus snapshot

MarketBeat’s analyst aggregation (as displayed today) shows:

Consensus rating:Moderate Buy (24 analysts), with 22 Buy, 1 Hold, 1 Sell. ^[26]
Consensus price target:$205.41 (with $269 high and $115 low). ^[27]

Specific targets highlighted in today’s reporting

From Dec. 19 analyst items:

Goldman Sachs:Buy, $225 target. ^[28]
Truist:Buy, $205 target. ^[29]

And from widely circulated coverage (including MarketBeat’s Dec. 19 write-up referencing recent analyst actions), HC Wainwright maintained a Buy rating and $230 target while trimming its FY2028 EPS estimate from 3.42 to 3.15. ^[30]

Taken together, the Street is signaling: reduced indication optionality, but not a collapsed long-term commercial thesis—at least not yet.

What long-term investors will watch next

Even for traders focused on today’s move, INSM is ultimately still a “catalyst stock.” The next leg—up or down—likely depends on whether Insmed can prove that the CRSsNP miss is contained, while the commercial and clinical engine keeps delivering.

Here are the big items investors are watching:

1) Brinsupri uptake metrics in non-CF bronchiectasis

Analysts are focused on early adoption signals and typically want multiple quarters of prescription and payer data to judge trajectory—something Goldman specifically referenced in today’s note. ^[31]

2) Progress on TPIP (pulmonary hypertension franchise buildout)

BioSpace notes Insmed’s stated intention to start a Phase 3 program for TPIP in pulmonary arterial hypertension in early 2026, and to launch a late-stage study in PH-ILD before year-end. ^[32]

3) Pipeline expansion via INS1148

Insmed’s plan to push INS1148 into Phase 2 studies in ILD and asthma creates a fresh set of milestones (trial initiations, early biomarker reads, safety updates) that could matter more as the CRSsNP story fades. ^[33]

4) Follow-on DPP-1 work (INS1033 timing)

Goldman’s note references INS1033 entering clinical trials in 2026, reinforcing that Insmed is thinking beyond a single-asset story. ^[34]

Key risks to keep in mind (especially after a “placebo problem” trial)

INSM’s rally-and-dip pattern over the last 48 hours is a reminder that biotech investing is rarely linear. The most discussed risks right now:

Clinical readthrough risk: A CRSsNP miss driven by placebo response can still raise questions about how cleanly brensocatib separates from placebo and background therapy in other inflammatory settings. ^[35]
Concentration risk: Even with multiple programs, investor confidence today is heavily tied to Brinsupri’s commercial ramp and the company’s ability to expand its respiratory footprint. ^[36]
Valuation sensitivity: When a stock has been priced for multiple “shots on goal,” losing even one (like CRSsNP) can compress multiples quickly—exactly what this week’s move demonstrated. ^[37]

Bottom line: Insmed stock is being repriced, not written off

As of Dec. 19, 2025, Insmed stock sits in a classic post-catalyst reset: one meaningful expansion effort (CRSsNP) is off the table, but multiple analysts publishing today are still holding constructive views on the core business.

Goldman Sachs reiterated Buy at $225 and pointed to pipeline depth and launch visibility over the next few quarters. ^[38]
Truist initiated/assumed coverage with Buy at $205, calling the pullback a chance to accumulate ahead of broader adoption. ^[39]
Aggregated forecasts still show a Moderate Buy consensus with a ~$205 average target. ^[40]