DGX — Q3 2026 Financial Report Analysis

Quest Diagnostics, the largest independent US medical lab company, grew third-quarter 2026 revenue 10.0% to $3.10 billion, and this time profit grew faster than sales. Operating income, the profit from running the business before interest and tax, rose 24.2% to $479 million. Diluted EPS (earnings per share, the profit attributable to each share) rose 28.7% to $2.78 under standard accounting rules (GAAP). On the company's adjusted basis, which strips out amortization and one-off items, EPS rose 15.4% to $3.00. Management raised its full-year 2026 revenue, EPS and cash-flow guidance for the third quarter in a row. On the same day Quest disclosed a cyberattack on one of its ordering systems, which it says has not materially disrupted operations.

Key figures

Diagnostic Solutions revenue is net revenues minus Diagnostic Information Services revenues; the release does not list it separately. Quest reports requisition volume and revenue per requisition only as percentage changes. The earnings release does not give an organic revenue growth rate, only organic volume. Because organic volume (14.4%) and total volume (14.5%) are almost the same, acquisitions contributed very little this quarter.

Source: Quest Diagnostics Q3 2026 earnings release (Form 8-K, Exhibit 99.1, filed October 22, 2026). The full Form 10-Q, which includes the management discussion and the breakdown of volume by customer, has not been filed yet.

Volume up, price per order down

Quest's lab business comes down to two numbers. Requisitions are the order forms that come with each patient sample; each lists the tests to run and who pays. Revenue per requisition is the average amount Quest collects per order. Revenue growth is roughly these two combined: +14.5% volume and -4.2% per order gives about +10% revenue, which matches the Diagnostic Information Services line (+10.2%).

The pattern is the same as in Q2, only stronger. Volume growth sped up from 13.1% to 14.5%, and the fall in revenue per order deepened from -2.8% to -4.2%. In Q2 the 10-Q explained both moves: the Corewell Health joint lab in Michigan (started January 2026) and expanded testing for Fresenius Medical Care dialysis clinics added about 9 points of volume. That work is mostly routine tests that pay less per order. The Q3 release doesn't repeat that breakdown. But Corewell will not reach its one-year anniversary until January 2027, so most of the volume jump and the lower price per order very likely have the same cause. The 10-Q will confirm it.

CEO Jim Davis credits "continued strength across our physician, hospital and consumer channels." The release also points to a deal to buy outreach lab assets from a Northeastern health system. It will add revenue once it closes, but that hasn't happened yet.

Margins turned back up

The key change from Q2 is profit. In Q2, adjusted operating margin fell 0.4 points because the new low-priced work diluted it. In Q3 it rose 0.4 points to 16.7%. Adjusted operating income grew 13.0%, faster than revenue's 10.0%. Management credits "productivity gains from automation and AI." On a GAAP basis, cost of services (the lab's direct cost of running tests) rose 10.1% to $2,055 million, about in line with revenue. Selling, general and administrative costs rose only 4.4% to $523 million. Most of the margin gain came from overhead growing much more slowly than sales.

What the headline numbers hide

• GAAP EPS growth of 28.7% overstates the improvement. A year ago the quarter carried heavier one-off charges: $11 million of restructuring, $22 million of other charges (including a $15 million legal charge and a $5 million impairment from exiting a business), and $39 million of amortization. This year: $3 million of restructuring, $4 million of other charges, $37 million of amortization and a $6 million gain, mostly a $4 million insurance recovery on legal matters. The gap between GAAP and adjusted EPS shrank from $0.44 to $0.22, and that alone accounts for much of the GAAP growth. The 15.4% adjusted figure is the better measure of the underlying business.
• No tax help this quarter. The GAAP effective tax rate was 23.8% ($99 million on $416 million of pre-tax income), about the same as 23.5% a year ago. Unlike Q2, when a tax settlement added $0.10 to adjusted EPS, this quarter's growth came from operations. Quest also excludes excess tax benefits on stock compensation from adjusted EPS ($0.05 this quarter).
• Buybacks and interest helped only a little. Diluted shares fell from 113 million to 112 million. Adjusted net income rose 14.2% and adjusted EPS 15.4%, so about one point of EPS growth came from the lower share count. Net interest expense fell to $61 million from $66 million.
• Cash conversion is fine, but customers are paying more slowly. Over nine months, operating cash flow was $1,486 million against net income of $924 million. The gap is normal for a lab company with large depreciation and amortization ($440 million). But accounts receivable (money owed by insurers and customers) rose 21.6% since year-end, from $1,408 million to $1,712 million, while nine-month revenue grew 9.8%. Receivables used $308 million of cash, compared with $153 million a year earlier. Most of that build happened in the first half ($259 million), so Q3 alone was more normal. It fits with large new customers whose bills take longer to collect, and it is worth watching.
• Guidance went up, not just the range narrowed. The revenue range moved to $12.065–$12.105 billion from $11.95–$12.05 billion, and the adjusted EPS midpoint rose $0.15 to $11.30.
• A new risk outside the numbers. In a separate 8-K, Quest said that on October 21, 2026 it learned of unauthorized access to its Quanum LSM system, which clients use to place orders and look up results. It believes "an unauthorized party accessed certain patient records." The full scope is still under investigation. The guidance does not include any cost for the incident, and Quest lists it as a risk factor.

Takeaway: This is the quarter in which the large, low-priced contracts started paying off. Revenue per order fell even further (-4.2%), but adjusted operating margin rose 0.4 points instead of falling, and adjusted EPS grew 15.4% with no help from taxes. The main new uncertainty is not operational: it is the patient-data breach disclosed the same day, whose cost and scope are still unknown.

Did last time's read hold up?

Our Q2 report said two figures would matter in Q3. The first was whether organic volume growth excluding Corewell and Fresenius would stay near 4%. The earnings release doesn't break that out, so we can't check it until the 10-Q is filed. Total organic volume did speed up from 13.0% to 14.4%. The second was whether adjusted operating margin would start to recover. It did: 16.7%, up 0.4 points, after a 0.4-point decline in Q2. We also warned that without another tax benefit, EPS growth would slow from Q2's 19%. It slowed to 15.4%. That is less of a slowdown than we feared, because higher margins made up for most of the missing tax benefit.

Guidance and outlook

Nine-month results were $9,035 million of revenue and $8.62 of adjusted EPS. Subtracting those from the new full-year ranges gives an implied fourth quarter of about $3.03–$3.07 billion of revenue and $2.63–$2.73 of adjusted EPS. That is below Q3's $3.10 billion and $3.00, partly because the holiday weeks usually mean fewer tests in the fourth quarter. The range does not look stretched.

Our read: The concern after Q2 was that Quest was buying volume at the expense of margin. Q3 eases that concern: overhead grew 4.4% while revenue grew 10%, and margin rose. The comparisons get harder from January 2027, when Corewell has been running for a full year and volume growth should fall back toward the underlying rate. Then the price-per-order drag should also fade. Three things to watch: the 10-Q's split of organic volume between the new contracts and the existing business; whether receivables keep growing faster than revenue; and anything Quest discloses about how many patients the Quanum breach affected and what it will cost. More detail is due at Quest's 2027 Investor Day on March 25, 2027.