THE NHS regulator Monitor is considering whether to investigate York Teaching Hospital NHS Foundation Trust.
Last year the watchdog went into the hospital due to concerns over emergency care and breast cancer referral times - a matter it said was addressed by the trust.
Now Monitor has put the trust "under review" which means it has "identified a concern but not yet taken action".
A significant number of foundation trusts nationally are subject to enforcement action or under review, with many struggling to balance finances due to funding.
Monitor did not confirm whether York is under review due to concerns over its forecast £9.7 million end-of-year debt.
It has rated the financial sustainability of the trust as 2 on a scale where 1 indicates the most serious risk and 4 the least risk.