In the fall of 2022, a team of Wall Street Journal reporters asked the federal Centers for Medicare and Medicaid Services (CMS) for access to Medicare data for a series on suspected overbilling in Medicare Advantage.
“We basically took the unusual step of asking CMS to treat a group of journalists as researchers for purposes of reviewing their massive repository of data,” said Christopher Weaver, an investigative reporter at the Journal.
“They agreed and gave us a data-use agreement that allowed us to access 100% of what’s called person-level Medicare and Medicaid claims over a 12-year period,” he explained. “That was every prescription filled, every trip to the doctor and every hospitalization in minute detail.”
The volume of data was prodigious. “It was kind of like being the dog that caught up with the car,” Weaver said. “Because suddenly we had to learn how to use and do something with literally billions upon billions of medical records.”
The Medicare program cost the federal government $1.12 trillion in 2024 and, of that amount, the private health insurers that operate Medicare Advantage plans were expected to get $500 billion to $600 billion, CMS data show. This year, total enrollment in Medicare is 69.7 million seniors aged 65 and older, 51.1% of whom are enrolled in Medicare Advantage and other health plans.
Journalists as researchers
After requesting the data, the reporters needed to show CMS that they could analyze and use the data competently as researchers would, Weaver said. CMS provided the data in August 2023 during the Biden administration. “I don’t know if we would be able to navigate that process now or not given that it was a different time with a different administration than we have now,” he said.
In addition to Weaver, others on the team were Anna Wilde Mathews, who covers health insurance; Mark Maremont, a senior editor for investigative reporting; Andrew Mollica, a graphics reporter; and Tom McGinty, an investigative reporter specializing in searching spreadsheets, databases and public records.
Once the team understood the data, they began reporting on how Medicare Advantage insurers — such as UnitedHealth Group, the nation’s largest health insurer, and CVS Health, the third largest — used questionable billing practices. Those practices cost taxpayers billions and jeopardized vulnerable patients, the team wrote. Among Medicare Advantage insurers in 2025, UnitedHealth Group had the most enrollees with 9.9 million members (29% of all seniors in MA plans), followed by Humana Inc. with 5.7 million (17%) and CVS Health Corp. with 4.1 million (12%), according to KFF.
For their work, the team was a finalist for the 2025 Pulitzer Prize in investigative reporting for producing “a comprehensive series showing how health insurers gamed the MA program to collect billions for nonexistent ailments while shunting expensive cases onto the public,” the prize committee wrote.
The series won an award from theInvestigative Reporters & Editors, the New York Press Club, and was a finalist for the Goldsmith Award from the Shorenstein Center at Harvard University. On the series landing page, Medicare Inc., the journal describes the work as “an investigation into the secret practices insurers use to pocket billions from Medicare.” Last year, KFF estimated that the federal government paid about 20% more to Medicare Advantage insurers than what it would have paid to deliver the same care in traditional Medicare, which amounts to $84 billion in additional spending.
Senate cites WSJ’s reporting
In addition to the awards above, the journal team and reporters from STAT news were cited more than two dozen times when the U.S. Senate Committee on the Judiciary published a 104-page report in January on MA overbilling: “How UnitedHealth Group Puts the Risk in Medicare Advantage Risk Adjustment.”
The committee’s majority staff report cited the journal and STAT news for their work uncovering the questionable strategies of MA insurers. The STAT news journalists were reporting on how UnitedHealth Group used the physician groups it acquired to boost profits for STAT’s Health Care’s Colossus series. The journal team and the STAT news journalists were doing their reporting at about the same time, Weaver commented.
“Our first article in the project came out in July 2024,” Weaver said in an interview. In that first article, “Insurers Pocketed $50 Billion From Medicare for Diseases No Doctor Treated,” the journalists explained that a UnitedHealth Group Medicare Advantage member in Boston got a $50 gift card from a nurse who “checked her over, asked her questions and diagnosed her with diabetic cataracts.” Each added diagnosis means Medicare pays insurers more, the team wrote.
For a Medicare Advantage member with diabetic cataracts, the insurer could get about $2,700 more annually at that time, the journal reported. But the Boston Medicare Advantage member didn’t have diabetes, the patient’s doctor told the Journal, or the cloudy vision sometimes caused by the disease.
From 2018 to 2021, the team’s analysis of billions of Medicare records showed how private insurers in the MA program made hundreds of thousands of questionable diagnoses that generated extra payments despite some charges being “outright wrong,” they wrote.
“The questionable diagnoses included some for potentially deadly illnesses, such as AIDS, for which patients received no subsequent care, and for conditions people couldn’t possibly have, the analysis showed,” the team wrote. “Often, neither the patients nor their doctors had any idea.”
The team found a wide spectrum of problems that contributed to overbilling, Weaver said. “It was a mix of fraud and a kind of gamesmanship and maybe some laxity on the part of the public officials who set up the system that made it so vulnerable to exploitation,” he said. “A lot of the diagnoses we found were about insurers adding diagnoses to people’s records that were questionable. Many of those diagnoses might have been anatomically plausible, and some certainly were accurate, but, in many cases, they weren’t diagnoses that anybody intended to treat.”
Words of caution for reporters
For journalists considering similar work, Weaver offered a warning: Without having the CMS data, reporters might struggle to report and write a series on how health insurers add diagnoses to patients’ records. “Essentially, it’s a business about manipulating data. How do you expose that without being able to look at the numbers?” Weaver asked. “It would have been hard to do those stories as convincingly as we did without the data we had.”
For such extensive reporting projects, there are high barriers to entry, he said. One member of the team needed to learn SAS programming, for example. In total, Weaver said, the team had to analyze some 40,000 lines of code for the 2024 series of articles. The journalists did hundreds of interviews and asked sources to send them documents to confirm their reporting.
“Also, patients had to find and send us their own medical records and sign the necessary releases,” he added.
“For journalists venturing into this type of reporting that combines some of the skills of health services research and claims analysis, I’d suggest starting smaller than we did,” Weaver advised. “Maybe start by looking at hospital or nursing home claims. Then you can build up some of the competencies you’ll need to translate that knowledge into doing more impactful stories like what we did.”
Resources
- UnitedHealth Books Hefty Charges, Issues Soft Full-Year Revenue Outlook, Anna Wilde Mathews, The Wall Street Journal, Jan. 27, 2026
- How Medicare Pays Medicare Advantage Plans: Issues and Policy Options, KFF, Nov. 20, 2025
- Medicare Advantage: Questionable Use of Health Risk Assessments Continues To Drive Up Payments to Plans by Billions, Office of Inspector General, Oct. 21, 2024
- The One-Hour Nurse Visits That Let Insurers Collect $15 Billion From Medicare, Anna Wilde Mathews, Christopher Weaver, Tom McGinty, Mark Maremont, Aug. 4, 2024
- Medicare’s Opioid Limits Didn’t Protect This Doctor’s Patients From Deadly Overdoses, Maremont, Weaver, McGinty, Mathews, Aug. 10, 2024
- The Sickest Patients Are Fleeing Private Medicare Plans—Costing Taxpayers Billions, Mathews, Weaver, McGinty, Nov. 11, 2024
- Insurers Collected Billions From Medicare for Veterans Who Cost Them Almost Nothing, Maremont, Weaver, McGinty, Dec. 2, 2024
- UnitedHealth’s Army of Doctors Helped It Collect Billions More From Medicare, Weaver, Mathews, McGinty, Dec/ 29, 2024
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