BYD, the Chinese automaker partly owned by billionaire Warren Buffet, slumped on Tuesday after it posted a sharp decline in net profit for the third quarter. The stock fell by 5.35 per cent to HK$ 14.86 as of 11:44 a.m. on Tuesday, compared with a decline of 0.48 per cent of the benchmark Hang Seng Index at the same time. The stock had fallen by as much as 7.01 per cent this morning.