UnitedHealth Group Inc. (UNH) is facing uncomfortable questions from Senate investigators about how it turned Medicare Advantage diagnosis rules into what the committee calls a profit engine. The Senate Judiciary Committee's investigation found that the health insurance giant deployed aggressive strategies to collect diagnoses that pumped up federal payments under the program.

Back in July 2025, UnitedHealth acknowledged it had started cooperating with formal criminal and civil investigations from the Department of Justice. The company says it stands behind its practices and is working cooperatively with investigators throughout the process.

This probe has been underway for at least a year, and it's gaining fresh momentum as former employees are now sitting down with federal investigators to share what they know.

The Medicare Advantage Payment System

Here's how this works: Medicare Advantage pays insurers a fixed amount to manage healthcare for seniors and people with disabilities. The twist is that insurers get higher payments when patients are diagnosed with expensive medical conditions. The idea is to compensate for sicker patients who cost more to treat.

According to the Senate report, UnitedHealth transformed that payment adjustment process into something much bigger than its original intent. Instead of simply reflecting patient health status, investigators say the company systematically hunted for diagnoses that would trigger higher government payments.

The committee's findings come from reviewing roughly 50,000 pages of internal UnitedHealth documents handed over last year at the request of Senator Chuck Grassley. Grassley started asking questions after a 2024 Wall Street Journal investigation reported that the insurer was systematically adding diagnoses that generated billions of dollars in additional federal payments.

That Journal investigation raised red flags about diagnoses that appeared questionable or lacked proper support, and noted that patients often never received treatment for the newly added conditions. UnitedHealth pushed back on those characterizations, with a company spokesperson telling the Journal that the insurer complies with Medicare rules and has performed well in audits of its diagnosis practices.

Inside UnitedHealth's Diagnosis Strategy

The Senate report doesn't formally accuse UnitedHealth of wrongdoing or issue specific recommendations. But it does lay out a detailed picture of how the company operated, including deploying nurses for in-home visits, offering financial incentives to physicians to consider additional diagnoses, and using artificial intelligence and data-mining tools to comb through medical records hunting for new conditions.

Investigators dug through training materials, internal studies, manuals, and diagnostic guidelines. In some cases, the report found, those guidelines encouraged staff to record diagnoses that triggered higher payments without confirming them through recommended testing. That's a problem because you're supposed to actually verify that a patient has a condition before billing Medicare for it.

The insurer has acknowledged that policy changes it made to address these issues contributed to weaker financial results last spring, which sent its share price tumbling. In December 2025, UnitedHealth disclosed initial findings from a sweeping independent review of its business practices, positioning the move as an early step toward greater transparency and operational improvement under new leadership.

More Trouble On Multiple Fronts

The Medicare diagnosis questions aren't UnitedHealth's only headache. In August 2025, two Democratic senators demanded information about the emergency relief loans the company provided to healthcare providers after a massive cyberattack in February 2024, and how it's collecting those debts.

That cyberattack was catastrophic, compromising the personal data of 190 million Americans and affecting around 900,000 doctors, 33,000 pharmacies, 5,500 hospitals, and 600 labs. It was one of the largest healthcare data breaches in U.S. history.

In March 2025, UnitedHealth's Optum Rx division said it would align payment models more closely to the costs pharmacies face from manufacturer pricing actions, with full implementation planned by January 2028.

UNH Price Action: UnitedHealth Group shares were down 2.51% at $335.35 at the time of publication on Monday.