Amazon.com, Inc. (AMZN) vs Quest Diagnostics Incorporated (DGX): Which Is the Better Buy in 2026?
As of 2026-06-19, AMZN is overvalued at $244, with a DCF intrinsic value of $211 and a margin of safety of -16%. DGX is overvalued at $195, with an intrinsic value of $154 and a margin of safety of -27%. Of the two, AMZN has the wider margin of safety.
Rewards
- ★Each dollar of retained earnings has created $5.34 of earning power — management is an exceptional capital allocator.
- ★Trailing P/E of 31.5x is 23% below the historical average of 40.6x — potentially undervalued relative to its own history.
- ★Altman Z-Score of 5.30 indicates very low bankruptcy risk — the company is firmly in the safe zone.
- ★4 insider purchases vs. 1 sell in the past 3 months — buying activity significantly outweighs selling.
Risks
- ⚠FCF yield of 0.4% is below 3%, meaning the market is pricing in substantial future growth to justify the current price.
- ⚠15 insider sales totaling $51.6M with no purchases in the past 3 months — insiders are reducing their exposure.
- ⚠Each dollar of retained earnings has produced only $0.36 of earning power — shareholders may have been better served by dividends.
- ⚠FCF yield of 6.3% suggests reasonable valuation assuming continued moderate growth.
Key Valuation Metrics
Learn more →Historical Fundamentals
Learn more →Price ÷ Earnings Per Share — how many years of current earnings you're paying for at today's price. Lower P/E may indicate undervaluation. The dashed forward point is the forward P/E — today's price ÷ analyst consensus EPS.
Price ÷ Earnings Per Share — how many years of current earnings you're paying for at today's price. Lower P/E may indicate undervaluation. The dashed forward point is the forward P/E — today's price ÷ analyst consensus EPS.
Price ÷ Earnings Per Share — how many years of current earnings you're paying for at today's price. Lower P/E may indicate undervaluation. The dashed forward point is the forward P/E — today's price ÷ analyst consensus EPS.
$1 Retained Earnings Test
Learn more →> $1 created per $1 retained = Value Creator · < $1 created = Value Destroyer
> $1 created per $1 retained = Value Creator · < $1 created = Value Destroyer
Buffett's "$1 Test": For every $1 of earnings retained, has management created at least $1 of market value?
> $1 created per $1 retained = Value Creator · < $1 created = Value Destroyer
Discounted Cash Flow (DCF) Analysis
Learn more →Reverse DCF — Market-Implied Growth
Learn more →What growth rate is the market pricing in at $244?
The market implies +15.3% Owner Earnings growth, below historical trends — potential opportunity.
Standard FCF implies a more demanding +45.0%, reflecting heavy growth investment expected to generate future returns.
What growth rate is the market pricing in at $195?
The market implies +11.6% Owner Earnings growth, above historical trends.
Standard FCF implies a demanding +7.9%, reflecting heavy growth investment.
Economic Moat Score
Learn more →Narrow moat with revenue predictability as the key competitive advantage. Improving margin stability would strengthen the moat.
Narrow moat with margin stability as the key competitive advantage. Improving roic consistency would strengthen the moat.
Forensic Accounting
Learn more →M-Score Trend
M-Score Trend
Beneish's 8-variable model estimates the probability of earnings manipulation. An M-Score above -1.78 signals elevated risk — companies in this range have historically been 3-5× more likely to be manipulating earnings. Scores between -2.22 and -1.78 fall in a grey zone warranting further investigation.
Ownership Breakdown
Learn more →High insider ownership aligns management incentives with shareholders. Institutional concentration can indicate smart-money conviction but also crowding risk.
Insider Buying Activity
Learn more →Open market purchases · includes direct & indirect ownership · excludes option exercises.
Insider Selling Activity
Learn more →Direct ownership only · excludes indirect, option exercises, planned (10b5-1) sales & derivatives.
🎭 Mr. Market's Mood
Learn more →"Market is pricing this stock without strong emotion in either direction"
"Market is pricing this stock without strong emotion in either direction"
Composite sentiment score based on market signals. Inspired by Buffett’s "Mr. Market" allegory — fear = potential opportunity, greed = potential risk. Must be used alongside fundamental analysis, not in isolation.
⚖️ Buffett Signal
Learn more →The Buffett Signal cross-references market sentiment with DCF valuation. Configure the DCF Analysis above to generate a signal.
The Buffett Signal cross-references market sentiment with DCF valuation. Configure the DCF Analysis above to generate a signal.
Frequently Asked Questions: AMZN vs DGX
Is Amazon.com, Inc. or Quest Diagnostics Incorporated more undervalued in 2026?▼
Based on our discounted cash flow model, AMZN trades at a -16.1% margin of safety (intrinsic value $211 vs. price $244), compared to DGX's -26.6% margin of safety (intrinsic $154 vs. $195).
Which stock has a wider economic moat, Amazon.com, Inc. or Quest Diagnostics Incorporated?▼
DGX scores 56/100 (Narrow moat), while AMZN scores 51/100 (Narrow moat). The moat score measures competitive advantage durability across ROIC consistency, margin stability, revenue predictability, and reinvestment efficiency.
Which company has better free cash flow, Amazon.com, Inc. or Quest Diagnostics Incorporated?▼
Quest Diagnostics Incorporated (DGX) generates a 6.3% free cash flow yield, compared to Amazon.com, Inc.'s 0.4%. A higher FCF yield means the business converts more of its market value into cash that can be returned to shareholders or reinvested.
Which stock has higher return on invested capital, Amazon.com, Inc. or Quest Diagnostics Incorporated?▼
AMZN earns 11.4% ROIC versus DGX's 8.9%. A higher ROIC means the company generates more profit per dollar of capital employed, a hallmark of durable competitive advantage in Buffett-style analysis.