The profitability of big corporate customers at Kasikornbank (KBank) is expected to fall by 1-2% this year, dragged down by the country's lukewarm economic recovery.
But executive vice-president Chongrak Rattanapian said the companies' strong payment ability would allow them to ride out any uncertainty.
KBank's large corporate clients have delivered annual sales and profit growth of 15% and 11% over the past four years, while their debt-to-equity ratio has fallen to 2.9 from 3.2.
With lower leverage, the ability to pay interest increases more than 20 times.
Kasikorn Research Center earlier this week cut its 2015 GDP growth forecast to 2.8% from 4%, citing tepid exports.
With a murky economic picture at home and uncertainty in the major economies, Thai businesses should pay closer attention to cost and risk management, Mr Chongrak said.
Several large companies are expanding beyond their home turf to capture greater business opportunities and take advantage of some major currencies' weakness amid a divergent global rebound.
In Asean, Thai companies' top investment destinations are Cambodia, Laos, Myanmar and Vietnam.
Local supply chains for construction, automotive and food have strong potential for expansion into regional and global markets.
Agriculture and related business are of concern to KBank due to a sharp decline in farm product prices.
The bank still expects to maintain the asset quality of its corporate banking business at a satisfactory level.
Its gross non-performing loans accounted for 2.15% of outstanding loans of 1.5 trillion baht at the end of last year, while corporate loans represented 30% of the bank's total loan portfolio.
In the meantime, HSBC has jumped on the bandwagon of growth projection cuts.
The London-based bank has trimmed its GDP growth forecast for Thailand to 3.6% from 4% due to slack in domestic demand, swelling household debt and challenging external conditions that act as headwinds against export growth.
"The remaining support for growth, besides tourism, is the slight uptick in private investment, as observed from factory permits and investment promotion applications," said Nalin Chutchotitham, a Bangkok-based economist at HSBC.
Public investment can also limit downside risks for economic growth, she said.
"Economic growth in the near term will likely be slower than previously envisioned as resources are channelled towards reform efforts," Ms Nalin said.
Many of the reforms involve long processes such as streamlining cumbersome bureaucratic procedures and modernising business- and investment-related legislation.
Another question mark is the possibility of changes to economic policies after the next election, Ms Nalin said.
KBANK shares closed yesterday on the Stock Exchange of Thailand at 226 baht, up one baht, in heavy trade worth 1.44 billion baht.