Prudential PLC (LSE:PRU) shares plunged 11.6% to 967.9p after reports that Chinese authorities had begun taxing returns from offshore insurance policies, threatening demand from mainland customers. The sell-off spread to other Asia-focused FTSE 100 companies, with HSBC Holdings PLC (LSE:HSBA, NYSE:HSBC) and Standard Chartered PLC (LSE:STAN) both dropping over 6%.