new federal budget measures affecting property investment. Shares in Commonwealth Bank of Australia recorded their largest one-day decline on record, falling 10.4 per cent after the bank released a trading update that disappointed investors and announced additional provisions for geopolitical risk. Chief executive Matt Comyn said the bank had set aside an extra $200 million to prepare for potential impacts from conflict in the Middle East and resulting supply chain disruptions. Other major Australian banks also closed lower on the Australian Securities Exchange, with Westpac Banking Corporation, Australia and New Zealand Banking Group and National Australia Bank all posting losses. Investor sentiment was further affected by federal budget changes that will limit negative gearing to newly built properties and replace the flat 50 per cent capital gains tax discount with an inflation-indexed model, with existing investments grandfathered. Despite the sharp sell-off in banking stocks, the S&P/ASX 200 finished only modestly lower as gains in other sectors helped offset the decline.