In March 2023, Swiss authorities strongarmed banking giant UBS into a $3.25 billion takeover of Credit Suisse to prevent it from going under, in a debacle that could have triggered a global banking crisis and shredded Switzerland's reputation for sound banking.

Credit Suisse is now a UBS subsidiary.

Singapore law firm Drew & Napier said the investors are claiming that Switzerland breached investment treaty obligations "when it unilaterally wrote down US$17 billion worth of" Additional Tier-1 ("AT1") bonds, rendering them worthless.

"They are claiming losses amounting to around US$250m, making it the largest claim against Switzerland in treaty arbitration to date," the law firm said.

The investors "have submitted trigger letters to Switzerland under various bilateral investment treaties between their home countries".

Issuing the "trigger letters" is the first step to reclaim their losses, and must be taken before the investors can commence arbitration proceedings, it added.

The parties must now engage in negotiations over the next six months to attempt to resolve the dispute amicably, said Mahesh Rai, Drew & Napier's lead counsel.

Under the bilateral investment treaties, "Switzerland is obligated to protect investors' rights and ensure that investors are treated fairly and equitably," according to the law firm.

Omni Bridgeway, a company that provides litigation financing and dispute resolution services, has entered into an arrangement with the investors to cover the costs of the action in exchange for a share of any damages recovered.

"We are continuing to accept sign-ups for additional investors from Singapore, Japan and Hong Kong to our action, and strongly encourage them to do so by early 2025 so that they can be included in the claim as well," Rai said.

"We are also looking to commence claims to assist affected investors from other jurisdictions such as Thailand and the Philippines, as many investors from these jurisdictions continue to express interest in the action that we are leading."