The risks are coming following years of mergers and acquisitions. The most recent deal saw Apollo Global Management LLC swallowing rural hospital chain LifePoint Health Inc. for $5.6 billion last month. Apollo declined to comment on the deal; LifePoint has until Aug. 22 to solicit other offers. Consolidation among other health-care players, such as CVS’s planned takeover of insurer Aetna Inc., could also pressure hospitals as payers push patients toward outpatient services.

There are already a lot of hospitals with high negative margins, consultancy Veda Partners health care policy analyst Spencer Perlman said, and that’s going to become unsustainable. Rural hospitals with a smaller footprint may have less room to negotiate rates with managed care companies and are often hobbled by more older and poorer patients.

Also wearing away at margins are technological improvements that allow patients to get more surgeries and imaging done outside of the hospital.