SHANGHAI—The Evergrande Group’s struggles to quickly sell off assets and avert defaulting on its $305.3 billion in liabilities is raising the risk of contagion for other privately-owned developers and fund managers analysts say. Worries over the ability of China’s second-largest property developer to make bank loan interest and wealth management product payments have led to a worsening sell-off in its bonds and shares in the past week. Evergrande’s offshore bonds have dropped to less than one-quarter of their face value, trading of its onshore bonds has been paused, and a stock price rout has deepened, knocking more than three-quarters off its market capitalization this year. “Telling property guys to de-leverage so quickly is like telling a 900-pound guy to drop to under 100 pounds,” said a fixed income asset manager who declined to be identified due to sensitivities around the issue. “It won’t be the obesity that kills him, but …