Headquarters of Shinhan, Woori, KB Kookmin and Hana in Seoul / Courtesy of each holding firms

Corporate financial soundness indicators for the country's top five financial groups are deteriorating, hamstrung by the plunging value of the Korean won against the U.S. dollar in the aftermath of President Yoon Suk Yeol's botched attempt to declare martial law and the ensuing political uncertainties, market watchers said Monday.

Most pronounced is about a 16 trillion won ($10 billion) increase in their risk-weighted assets (RWAs) eroding the common equity tier 1 (CET1) ratio over the past month.The won-denominated figures in turn lower both the liquidity coverage ratios (LCR) and the Bank for International Settlements (BIS) capital ratio — a major red flag.

RWA measures financial firms' assets adjusted for their potential for risks. Included are loans, receivables and offshore investments.

A depreciation of 10 won in the Korean currency pushes up the RWAs of the five groups by nearly 2 trillion won. The value of the won plummeted to an intraday and 15-year low of 1,487.17 won against the greenback on Friday, more than 80 won weaker from the 3:30 p.m. close price of 1,402.43, Dec. 3, hours before the martial law declaration.

The combined RWAs of the groups surpassed 1,370 trillion won as of the third quarter, while that of their banking subsidiaries stood at 979.35 trillion won.

"A 10 won depreciation in the Korean currency translates to a decline of about 2 to 3 basis points in CET1 ratio," a Hana Bank official said.

According to market data, the expected RWA exposures for KB, Shinhan, Hana, Woori and NH NongHyup increased by more than 16 trillion won between Dec. 3 and Friday.

The groups are under emergency operation, anticipating the extended decline of the Korean currency well into the next few quarters.

Among their priorities are providing assistance for small and medium-sized enterprises (SMEs), especially businesses hit by higher import prices, borrowers with foreign currency-denominated debts and those with impending settlement demands.

Woori Financial Group chair Yim Jong-yong called for a long-term approach in countering the sharp weakening of the Korean currency, Sunday.

"The supply of liquidity into the market should remain undisruptive from the ongoing political developments," he said during a meeting with group executives.

Weaker won-vulnerable businesses and self-employed groups will be closely monitored, he added. Prompt financial assistance for small businesses should proceed as directed by the financial regulators.

Bank of Korea Gov. Rhee Chang-yong said stabilizing the financial and foreign exchange markets in times of heightened volatility will take priority.

"Any signs of market dislocation will be contained, neutralized by immediate market stabilization measures," he said during a meeting with the top financial and economic policy authorities on Monday.

Korea has net foreign asset positions of $977.8 billion. The country's foreign currency reserves remain at $415.4 billion, the 9th largest globally.

The central bank has injected about 38.6 trillion won into the market liquidity in the form of repurchase agreements (repos) expansion since Dec. 4.