Which European stock exchange suffered the biggest one-day percentage fall during the 1873 Panic?

The Vienna Stock Exchange suffered the biggest one-day percentage fall during the 1873 Panic.

The crisis is often called the Gründerkrach in Austria and Germany. On May 9, 1873, a wave of selling struck Vienna after years of speculative investment in railways, property, and companies. The exchange suffered a collapse of confidence, and many newly formed enterprises failed.

The panic spread through interconnected European financial markets and later reached the United States. It marked the end of a period of rapid expansion known in Central Europe as the Gründerzeit. Banking failures and falling asset prices contributed to a long economic downturn.

The 1873 event is sometimes remembered mainly as an American panic, but its immediate stock-market shock began in Vienna. The later U.S. crisis followed the failure of Jay Cooke & Company in September 1873.