Bank of America Corp. posted a higher-than-expected quarterly operating profit amid improvement in its loan portfolio.

But some analysts questioned whether BofA, the nation’s largest bank by assets, could continue to generate profits from cutting reserves for bad loans.

"The decreasing risk provisions is something that we’ve seen happening at all banks. The question for BofA is whether it can continue that trend," said Heinz-Gerd Sonnenschein, strategist at Postbank in Bonn.

BofA is the third big bank to beat third-quarter earnings estimates, after JPMorgan Chase & Co. and Citigroup Inc. BofA shares rose 9 cents to $12.43 in premarket trade.

Excluding a non-cash goodwill charge, Charlotte, N.C.-based BofA reported earnings of $3.1 billion, or 27 cents per share. Analysts had expected 16 cents per share, according to Thomson Reuters I/B/E/S.

Including a previously announced $10.4 billion goodwill charge for its card business, the bank had a net loss of $7.3 billion, or 77 cents per share, compared with a loss of $2.2 billion, or 26 cents a share, a year ago.

Revenue, net of interest expenses, was $26.9 billion, up 2.2 percent from a year earlier.

The bank, like its peers, reported an improving credit outlook. Net charge-offs declined 24 percent from the second quarter to $7.2 billion, and its provision for credit losses was $5.4 billion, down by nearly half from a year earlier.

BofA announced the goodwill charge for its global card services unit during its second quarter earnings announcement. It cited a new law limiting the fees banks can charge for processing debit card transactions.

BofA projected it could lose between $1.8 billion and $2.3 billion in annual debit card revenue as a result of the law.

BofA shares fell 8.4 percent during third quarter, while the KBW Bank Index .BKX was flat.