Japan's financial services minister says regulators will look into the situation following warnings of massive losses by global banks.
Aso Taro said on Friday that the Financial Services Agency needs to share information with the Bank of Japan and authorities overseas, and to keep a close watch on how the situation develops.
Aso also said he understands that the potential impact will be limited, and will not jeopardize the overall financial health of the firms involved.
His comments come after Japan's Nomura Holdings and Mitsubishi UFJ Securities Holdings said they could incur huge losses from dealings with a US client.
Swiss banking giant Credit Suisse made a similar statement.
Another Japanese firm, Mizuho Financial Group, is also reportedly facing a possible 100-million dollar loss from deals believed to be linked to the same client.