Comprehensive Stock Comparison
Compare Ardelyx, Inc. (ARDX) vs United Therapeutics Corporation (UTHR) vs Zai Lab Limited (ZLAB) vs Amarin Corporation plc (AMRN) vs Alkermes plc (ALKS) Stock
Analyze side-by-side fundamentals, valuation, growth, and profitability to decide which stock is the better buy.
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Quick Verdict
| Category | Winner | Why |
|---|---|---|
| Growth | ARDX | 22.1% revenue growth vs AMRN's -25.5% |
| Value | UTHR | Lower P/E (16.9x vs 32.0x) |
| Quality / Margins | UTHR | 41.9% net margin vs ZLAB's -38.1% |
| Stability / Safety | UTHR | Beta 0.43 vs ZLAB's 0.99 |
| Dividends | Tie | Neither pays a meaningful dividend |
| Momentum (1Y) | UTHR | +57.4% vs ZLAB's -44.5% |
| Efficiency (ROA) | UTHR | 16.9% ROA vs ZLAB's -15.0%, ROIC 21.1% vs -42.8% |
Who Each Stock Is For
Income & stability
Growth exposure
Long-term compounding (10Y)
Sleep-well-at-night portfolio
Defensive / Recession hedge
Business Model
What each company does and how it makes money
Ardelyx is a biopharmaceutical company that develops and commercializes novel medicines for gastrointestinal and cardiorenal diseases. It generates revenue primarily from sales of its FDA-approved drug tenapanor — marketed as IBSRELA for irritable bowel syndrome with constipation and XPHOZAH for hyperphosphatemia in chronic kidney disease patients — along with partnership milestone payments and royalties from international licensing deals. The company's competitive advantage lies in its proprietary NHE3 inhibitor technology platform, which enables development of first-in-class oral therapies targeting specific ion transport pathways with potentially better safety profiles than existing treatments.
United Therapeutics is a biotechnology company focused on developing and commercializing therapies for pulmonary arterial hypertension and other rare diseases. It generates revenue primarily from its portfolio of PAH treatments — including Remodulin, Tyvaso, and Orenitram — which account for the vast majority of its sales. The company's competitive advantage lies in its deep expertise in prostacyclin therapies and its vertically integrated manufacturing capabilities for complex drug delivery systems.
Zai Lab is a biopharmaceutical company that licenses, develops, and commercializes innovative therapies for oncology, autoimmune disorders, and infectious diseases primarily in Greater China. It generates revenue through product sales of its commercialized drugs — like Zejula for ovarian cancer and NUZYRA for bacterial infections — supplemented by milestone payments and royalties from its extensive partnership network. The company's key advantage lies in its strategic licensing model that gives it exclusive rights to promising late-stage and commercial-stage therapies for the Greater China market, allowing it to build a diversified portfolio without bearing full R&D costs.
Amarin Corporation is a pharmaceutical company focused on developing and commercializing cardiovascular therapeutics. It generates nearly all its revenue from VASCEPA — a prescription omega-3 fatty acid product for reducing triglyceride levels — sold primarily to wholesalers and specialty pharmacies. Its key advantage is patent protection and regulatory exclusivity for VASCEPA, though this moat faces challenges from generic competition.
Alkermes is a biopharmaceutical company that develops and commercializes medicines for central nervous system disorders and other serious conditions. It generates revenue primarily from product sales of its proprietary drugs like VIVITROL and ARISTADA — which treat addiction and schizophrenia — along with royalties from partnered products and manufacturing services. The company's competitive advantage lies in its specialized drug delivery technologies that enable long-acting injectable formulations, creating significant barriers to entry for competitors.
Revenue Breakdown by Segment
How each company's revenue is distributed across its business units
Financial Metrics Comparison
Side-by-side fundamentals across 5 stocks. BestLagging
Financial Scorecard
UTHR leads in 5 of 6 categories (Financial Metrics, Valuation Metrics). ARDX leads in 1 (Total Returns).
Financial Metrics (TTM)
UTHR is the larger business by revenue, generating $3.2B annually — 14.0x AMRN's $227M. UTHR is the more profitable business, keeping 41.9% of every revenue dollar as net income compared to ZLAB's -38.1%. On growth, AMRN holds the edge at +17.4% YoY revenue growth, suggesting stronger near-term business momentum.
| Metric | ARDXArdelyx, Inc. | UTHRUnited Therapeuti… | ZLABZai Lab Limited | AMRNAmarin Corporatio… | ALKSAlkermes plc |
|---|---|---|---|---|---|
| RevenueTrailing 12 months | $398M | $3.2B | $460M | $227M | $1.5B |
| EBITDAEarnings before interest/tax | -$35M | $1.6B | -$218M | -$93M | $281M |
| Net IncomeAfter-tax profit | -$57M | $1.3B | -$176M | -$86M | $242M |
| Free Cash FlowCash after capex | -$55M | $1.0B | -$159M | -$22M | $520,800 |
| Gross MarginGross profit ÷ Revenue | +88.9% | +87.9% | +58.6% | +38.9% | +86.3% |
| Operating MarginEBIT ÷ Revenue | -9.5% | +46.9% | -49.9% | -42.5% | +17.2% |
| Net MarginNet income ÷ Revenue | -14.2% | +41.9% | -38.1% | -38.0% | +16.4% |
| FCF MarginFCF ÷ Revenue | -13.9% | +32.7% | -34.5% | -9.6% | +0.0% |
| Rev. Growth (YoY)Latest quarter vs prior year | +12.3% | +7.4% | +17.0% | +17.4% | -10.6% |
| EPS Growth (YoY)Latest quarter vs prior year | — | +23.7% | +43.8% | +69.7% | -67.0% |
Valuation Metrics
At 18.1x trailing earnings, UTHR trades at a 14% valuation discount to ALKS's 21.0x P/E. On an enterprise value basis, UTHR's 12.9x EV/EBITDA is more attractive than ALKS's 15.9x.
| Metric | ARDXArdelyx, Inc. | UTHRUnited Therapeuti… | ZLABZai Lab Limited | AMRNAmarin Corporatio… | ALKSAlkermes plc |
|---|---|---|---|---|---|
| Market CapShares × price | $1.6B | $22.0B | $21.3B | $5.7B | $5.0B |
| Enterprise ValueMkt cap + debt − cash | $1.7B | $20.4B | $20.8B | $5.6B | $4.5B |
| Trailing P/EPrice ÷ TTM EPS | -25.19x | 18.09x | -12.01x | -3.45x | 21.05x |
| Forward P/EPrice ÷ next-FY EPS est. | 401.84x | 16.90x | — | — | 32.04x |
| PEG RatioP/E ÷ EPS growth rate | — | 0.94x | — | — | — |
| EV / EBITDAEnterprise value multiple | — | 12.95x | — | — | 15.89x |
| Price / SalesMarket cap ÷ Revenue | 3.91x | 6.91x | 46.21x | 25.11x | 3.38x |
| Price / BookPrice ÷ Book value/share | 9.46x | 3.40x | 2.94x | 0.58x | 2.79x |
| Price / FCFMarket cap ÷ FCF | — | 21.13x | — | — | 9571.39x |
Profitability & Efficiency
UTHR delivers a 18.8% return on equity — every $100 of shareholder capital generates $19 in annual profit, vs $-37 for ARDX. AMRN carries lower financial leverage with a 0.02x debt-to-equity ratio, signaling a more conservative balance sheet compared to ARDX's 1.25x. On the Piotroski fundamental quality scale (0–9), UTHR scores 7/9 vs AMRN's 2/9, reflecting strong financial health.
| Metric | ARDXArdelyx, Inc. | UTHRUnited Therapeuti… | ZLABZai Lab Limited | AMRNAmarin Corporatio… | ALKSAlkermes plc |
|---|---|---|---|---|---|
| ROE (TTM)Return on equity | -36.7% | +18.8% | -24.5% | -18.8% | +13.3% |
| ROA (TTM)Return on assets | -11.6% | +16.9% | -15.0% | -13.1% | +9.7% |
| ROICReturn on invested capital | -10.8% | +21.1% | -42.8% | -18.7% | +14.9% |
| ROCEReturn on capital employed | -10.6% | +21.4% | -27.9% | -17.0% | +14.4% |
| Piotroski ScoreFundamental quality 0–9 | 3 | 7 | 3 | 2 | 5 |
| Debt / EquityFinancial leverage | 1.25x | — | 0.31x | 0.02x | 0.04x |
| Net DebtTotal debt minus cash | $140M | -$1.6B | -$455M | -$113M | -$518M |
| Cash & Equiv.Liquid assets | $68M | $1.6B | $680M | $121M | $588M |
| Total DebtShort + long-term debt | $208M | $0 | $224M | $8M | $70M |
| Interest CoverageEBIT ÷ Interest expense | -1.27x | 88.89x | -48.75x | -7085.14x | 23.55x |
Total Returns (with DRIP)
A $10,000 investment in ARDX five years ago would be worth $38,081 today (with dividends reinvested), compared to $1,115 for AMRN. Over the past 12 months, UTHR leads with a +57.4% total return vs ZLAB's -44.5%. The 3-year compound annual growth rate (CAGR) favors ARDX at 31.5% vs AMRN's -30.2% — a key indicator of consistent wealth creation.
| Metric | ARDXArdelyx, Inc. | UTHRUnited Therapeuti… | ZLABZai Lab Limited | AMRNAmarin Corporatio… | ALKSAlkermes plc |
|---|---|---|---|---|---|
| YTD ReturnYear-to-date | +6.5% | +1.4% | +10.9% | +0.6% | +6.5% |
| 1-Year ReturnPast 12 months | +22.2% | +57.4% | -44.5% | +27.3% | -12.3% |
| 3-Year ReturnCumulative with dividends | +127.4% | +104.8% | -48.3% | -66.0% | +12.6% |
| 5-Year ReturnCumulative with dividends | +280.8% | +194.2% | -88.1% | -88.9% | +56.8% |
| 10-Year ReturnCumulative with dividends | +170.7% | +313.2% | -31.2% | -52.7% | -6.7% |
| CAGR (3Y)Annualised 3-year return | +31.5% | +27.0% | -19.7% | -30.2% | +4.0% |
Risk & Volatility
UTHR is the less volatile stock with a 0.43 beta — it tends to amplify market swings less than ZLAB's 0.99 beta. A beta below 1.0 means the stock typically moves less than the S&P 500. UTHR currently trades 93.8% from its 52-week high vs ZLAB's 43.3% drawdown — a narrower gap to the peak suggests stronger recent price momentum.
| Metric | ARDXArdelyx, Inc. | UTHRUnited Therapeuti… | ZLABZai Lab Limited | AMRNAmarin Corporatio… | ALKSAlkermes plc |
|---|---|---|---|---|---|
| Beta (5Y)Sensitivity to S&P 500 | 0.62x | 0.43x | 0.99x | 0.84x | 0.61x |
| 52-Week HighHighest price in past year | $8.40 | $537.00 | $44.34 | $20.90 | $36.32 |
| 52-Week LowLowest price in past year | $3.21 | $266.98 | $15.96 | $7.08 | $25.17 |
| % of 52W HighCurrent price vs 52-week peak | +78.0% | +93.8% | +43.3% | +66.0% | +82.9% |
| RSI (14)Momentum oscillator 0–100 | 46.1 | 58.6 | 57.7 | 40.0 | 39.0 |
| Avg Volume (50D)Average daily shares traded | 4.1M | 274K | 622K | 76K | 1.6M |
Analyst Outlook
Analyst consensus: ARDX as "Buy", UTHR as "Buy", ZLAB as "Buy", AMRN as "Hold", ALKS as "Buy". Consensus price targets imply 159.5% upside for ARDX (target: $17) vs -84.3% for AMRN (target: $2).
| Metric | ARDXArdelyx, Inc. | UTHRUnited Therapeuti… | ZLABZai Lab Limited | AMRNAmarin Corporatio… | ALKSAlkermes plc |
|---|---|---|---|---|---|
| Analyst RatingConsensus buy/hold/sell | Buy | Buy | Buy | Hold | Buy |
| Price TargetConsensus 12-month target | $17.00 | $563.17 | $35.00 | $2.17 | $46.00 |
| # AnalystsCovering analysts | 16 | 30 | 11 | 18 | 28 |
| Dividend YieldAnnual dividend ÷ price | — | — | — | — | — |
| Dividend StreakConsecutive years of raises | — | 1 | — | — | 0 |
| Dividend / ShareAnnual DPS | — | — | — | — | — |
| Buyback YieldShare repurchases ÷ mkt cap | 0.0% | +4.5% | 0.0% | 0.0% | 0.0% |
Historical Charts
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Chart 1Total Return — 5 Years (Rebased to 100)
| Stock | Mar 20 | Feb 26 | Change |
|---|---|---|---|
| Ardelyx, Inc. (ARDX) | 100 | 432.78 | +332.8% |
| United Therapeutics… (UTHR) | 100 | 457.48 | +357.5% |
| Zai Lab Limited (ZLAB) | 100 | 28.99 | -71.0% |
| Amarin Corporation … (AMRN) | 100 | 4.66 | -95.3% |
| Alkermes plc (ALKS) | 100 | 164.6 | +64.6% |
Ardelyx, Inc. (ARDX) returned +281% over 5 years vs Amarin Corporation … (AMRN)'s -89%. A $10,000 investment in ARDX 5 years ago would be worth $38,081 today (including dividends reinvested).
Chart 2Revenue Growth — 10 Years
| Stock | 2016 | 2025 | Change |
|---|---|---|---|
| Ardelyx, Inc. (ARDX) | $24M | $407M | +1595.3% |
| United Therapeutics… (UTHR) | $1.6B | $3.2B | +99.1% |
| Zai Lab Limited (ZLAB) | $0.00 | $460M | — |
| Amarin Corporation … (AMRN) | $130M | $229M | +75.7% |
| Alkermes plc (ALKS) | $746M | $1.5B | +97.9% |
Ardelyx, Inc.'s revenue grew from $24M (2016) to $407M (2025) — a 37.0% CAGR. United Therapeutics Corporation's revenue grew from $1.6B (2016) to $3.2B (2025) — a 7.9% CAGR.
Chart 3Net Margin Trend — 10 Years
| Stock | 2016 | 2025 | Change |
|---|---|---|---|
| Ardelyx, Inc. (ARDX) | -4.7% | -15.1% | -223.3% |
| United Therapeutics… (UTHR) | 44.6% | 41.9% | -6.1% |
| Zai Lab Limited (ZLAB) | -1074.3% | -38.1% | +96.4% |
| Amarin Corporation … (AMRN) | -66.4% | -35.9% | +45.8% |
| Alkermes plc (ALKS) | -28.0% | 16.4% | +158.6% |
Ardelyx, Inc.'s net margin went from -5% (2016) to -15% (2025). United Therapeutics Corporation's net margin went from 45% (2016) to 42% (2025).
Chart 4P/E Ratio History — 8 Years
| Stock | 2017 | 2025 | Change |
|---|---|---|---|
| United Therapeutics… (UTHR) | 15.9 | 17.5 | +10.1% |
| Alkermes plc (ALKS) | 13.2 | 19.6 | +48.5% |
United Therapeutics Corporation has traded in a 8x–22x P/E range over 8 years; current trailing P/E is ~18x. Alkermes plc has traded in a 13x–20x P/E range over 3 years; current trailing P/E is ~21x.
Chart 5EPS Growth — 10 Years
| Stock | 2016 | 2025 | Change |
|---|---|---|---|
| Ardelyx, Inc. (ARDX) | -2.8 | -0.26 | +90.7% |
| United Therapeutics… (UTHR) | 15.25 | 27.86 | +82.7% |
| Zai Lab Limited (ZLAB) | -39.7 | -1.6 | +96.0% |
| Amarin Corporation … (AMRN) | -8.2 | -4 | +51.2% |
| Alkermes plc (ALKS) | -1.38 | 1.43 | +203.6% |
Ardelyx, Inc.'s EPS grew from $-2.80 (2016) to $-0.26 (2025). United Therapeutics Corporation's EPS grew from $15.25 (2016) to $27.86 (2025) — a 7% CAGR.
Chart 6Free Cash Flow — 5 Years
Ardelyx, Inc. generated $-44M FCF in 2025 (+72% vs 2021). United Therapeutics Corporation generated $1B FCF in 2025 (+118% vs 2021).
ARDX vs UTHR vs ZLAB vs AMRN vs ALKS: Key Questions Answered
9 questions · data-driven answers · updated daily
01Is ARDX or UTHR or ZLAB or AMRN or ALKS a better buy right now?
United Therapeutics Corporation (UTHR) offers the better valuation at 18.1x trailing P/E (16.9x forward), making it the more compelling value choice. Analysts rate Ardelyx, Inc. (ARDX) a "Buy" — based on 16 analyst ratings — the highest consensus in this comparison. The "better buy" depends entirely on your goals: growth investors should weight revenue trajectory, value investors should weight P/E and PEG, and income investors should weight dividend yield and streak.
02Which has the better valuation — ARDX or UTHR or ZLAB or AMRN or ALKS?
On trailing P/E, United Therapeutics Corporation (UTHR) is the cheapest at 18.1x versus Alkermes plc at 21.0x. On forward P/E, United Therapeutics Corporation is actually cheaper at 16.9x.
03Which is the better long-term investment — ARDX or UTHR or ZLAB or AMRN or ALKS?
Over the past 5 years, Ardelyx, Inc. (ARDX) delivered a total return of +280.8%, compared to -88.9% for Amarin Corporation plc (AMRN). A $10,000 investment in ARDX five years ago would be worth approximately $38K today (assuming dividends reinvested). Over 10 years, the gap is even starker: UTHR returned +313.2% versus AMRN's -52.7%. Past returns do not guarantee future results, and the stock with the higher historical return may already have its best growth priced in.
04Which is safer — ARDX or UTHR or ZLAB or AMRN or ALKS?
By beta (market sensitivity over 5 years), United Therapeutics Corporation (UTHR) is the lower-risk stock at 0.43β versus Zai Lab Limited's 0.99β — meaning ZLAB is approximately 129% more volatile than UTHR relative to the S&P 500. On balance sheet safety, Amarin Corporation plc (AMRN) carries a lower debt/equity ratio of 2% versus 125% for Ardelyx, Inc. — giving it more financial flexibility in a downturn.
05Which has better profit margins — ARDX or UTHR or ZLAB or AMRN or ALKS?
United Therapeutics Corporation (UTHR) is the more profitable company, earning 41.9% net margin versus -38.1% for Zai Lab Limited — meaning it keeps 41.9% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: UTHR leads at 46.9% versus -49.9% for ZLAB. At the gross margin level — before operating expenses — ARDX leads at 90.3%, reflecting greater pricing power or product mix advantage. Stronger margins indicate durable pricing power, lower cost of revenue, or higher mix of software/services. They are one of the clearest signs of business quality.
06Is ARDX or UTHR or ZLAB or AMRN or ALKS more undervalued right now?
On forward earnings alone, United Therapeutics Corporation (UTHR) trades at 16.9x forward P/E versus 401.8x for Ardelyx, Inc. — 384.9x cheaper on a one-year earnings basis. Analyst consensus price targets imply the most upside for ARDX: 159.5% to $17.00.
07Which pays a better dividend — ARDX or UTHR or ZLAB or AMRN or ALKS?
None of the stocks in this comparison currently pay a material dividend. All are effectively zero-yield and should be held for capital appreciation rather than income.
08Is ARDX or UTHR or ZLAB or AMRN or ALKS better for a retirement portfolio?
For long-horizon retirement investors, United Therapeutics Corporation (UTHR) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 0.43), +313.2% 10Y return). Both have compounded well over 10 years (UTHR: +313.2%, ZLAB: -31.2%), confirming both are viable long-term holds — but the lower-volatility option typically results in less emotional selling during corrections. Retirement portfolios generally favour predictability over maximum returns. Consult a financial advisor before making allocation decisions.
09What are the main differences between ARDX and UTHR and ZLAB and AMRN and ALKS?
Both stocks operate in the Healthcare sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both. These fundamental differences mean investors should not choose between them on a single metric — the "better stock" depends entirely on which of these characteristics aligns with your investment strategy.
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