SHANGHAI (Reuters) -Shares in Chinese automakers such as BYD, Nio and Geely tumbled on Monday after industry leader BYD offered fresh incentives on over 20 models and the CEO of Great Wall Motors warned that the world's largest auto industry was in an unhealthy state. The Hong Kong-listed shares of BYD Co Ltd closed 8.6% lower, while Geely Auto fell 9.5%. Chinese electric vehicle giant BYD over the weekend announced a fresh round of subsidies and incentives for more than 20 models, which reduced the starting price of its cheapest model, the pure battery-powered Seagull hatchback, to 55,800 yuan ($7,765).