Who owns Sonora Quest Laboratories LLC

Sonora Quest Laboratories LLC - Profile

Sonora Quest Laboratories is a clinical laboratory business operating across Arizona, formed in July 1997 when Samaritan Health System, now part of Banner Health, put the commercial laboratory arm of Laboratory Sciences of Arizona together with Quest Diagnostics of Arizona. Banner supplies the hospital laboratory network and patient volume and Quest supplies national testing platforms, esoteric test menus and laboratory operating scale. It employs roughly 3,900 people, runs more than 70 patient service centres and performs over 100 million diagnostic tests a year, covering routine chemistry and haematology, molecular testing, prescription drug monitoring, genetics and genomics, and anatomic pathology. About 95 percent of its testing is done at its own facilities in Phoenix, Tucson and Yuma, and it is accredited by the College of American Pathologists.

The disclosed stakes

One row per position. Where a holder reports the same company in two share classes, both rows are shown rather than summed, because the class is part of a position's identity.

Where each figure comes from

A private stake has no ownership form behind it, so the source is always the holder's own filing or disclosure. Anything modelled says so, with the arithmetic.

• Quest Diagnostics Incorporated. Exhibit 21.1 to the FY2025 10-K lists 'Sonora Quest Laboratories LLC (AZ)' at 49%, the only entity in the entire subsidiaries/JV/affiliates exhibit where Quest holds a MINORITY stake in an operating diagnostic-testing business (every other JV in the exhibit is majority-Quest-owned). Written here as 49, not 0.49. This is very likely the unnamed 'diagnostic information services joint venture' the 10-K's Equity Method Investees note describes ('Our equity method investees primarily consist of a diagnostic information services joint venture and an investment in a fund that purchases strategic holdings in private companies in the healthcare industry... generally between 20% and 49%... accounted for under the equity method'): 49% sits exactly at the top of that stated range, and no other Quest JV in Exhibit 21.1 is a minority stake. That link is an inference from two consistent filed facts, not a statement the 10-K makes explicitly by name, so it is flagged rather than asserted as certain. No individual carrying value is disclosed: Investments in equity method investees was a single combined balance of $136 million at 31 Dec 2025 and $137 million at 30 Jun 2026, covering BOTH this JV and the unnamed healthcare-strategic-holdings fund, with no split by investee anywhere in the 10-K or 10-Q, so per the combined-balance rule value_usd stays null here. sourcesource 2