The IMF urged Switzerland on Thursday to strengthen its financial sector regulation as supervising UBS has become "more challenging" since it grew into a global banking behemoth after its takeover of Credit Suisse.
Switzerland's biggest bank was strongarmed by the government into buying Credit Suisse last year over fears that the second largest lender in the country might go under and spark a global financial crisis.
"Lessons from the CS (Credit Suisse) case should inform further reforms to strengthen the regulatory and supervisory framework," the IMF said in a statement concluding its annual staff mission to Switzerland.
Like UBS, Credit Suisse was among 30 international banks deemed too big to fail due to their importance in the global banking architecture.
The merger raised serious concerns in Switzerland around jobs, competition and the size of the resulting bank relative to the Swiss economy.
"The complexity of the combined bank's global operations also makes supervision more challenging," the International Monetary Fund said.
"In the event of future crisis, the previous merger options may no longer be feasible," Pelin Berkmen, the head of the IMF delegation, warned at a press conference.
The Washington-based institution noted that UBS is the largest "G-SIB" -- global systematically important bank -- relative to its home country's economy.
The IMF said the "powers and resources" of the Swiss financial sector's supervisor must be increased "to enable early and effective intervention" when necessary.
The G20's Financial Stability Board, set up following the 2007-2008 global financial crisis to lead industry reforms, made a similar recommendation in February.
The Swiss Financial Market Supervisory Authority (FINMA) has also called for increased powers to punish bad banks.
UBS bought Credit Suisse at the bargain price of $3.25 billion.
The bank initially reported a net profit for 2023 of $29 billion but it published a revised figure of $27.8 billion on Thursday after reviewing the fair-value estimate of the deal.
The IMF said the Swiss economy "boasts strong fundamentals" and growth is "expected to recover gradually this year" to 1.3 percent, followed by 1.4 percent in 2025.
But it added the country faces "several challenges" including "mounting spending pressures", future financing gaps in the pension system and vulnerabilities in the real estate sector.