AllianceBernstein is preparing to file a lawsuit against the Swiss Confederation regarding the treatment of AT1 bonds during UBS's acquisition of Credit Suisse.

The US asset manager intends to seek $225 million in damages after the Swiss Financial Market Supervisory Authority (FINMA) declared $17 billion worth of these bonds as worthless, resulting in significant losses for investors.

AllianceBernstein will join as a plaintiff next month in a broader legal action initiated by law firm Quinn Emanuel Urquhart & Sullivan on behalf of Credit Suisse bondholders.

This addition is expected to increase the total value of the lawsuit to approximately $375 million.

The law firm argues that the Swiss government's involvement in the deal constituted unlawful interference with investors' property rights.

The recent ruling by FINMA, which considered the public sector's support for Credit Suisse as a triggering event for such actions, has led to numerous legal challenges from affected investors.