Thomas and Raymond Kwok, the billionaire co-chairmen of Hong Kong mega-developer Sun Hung Kai Properties (0016.HKG), were arrested Thursday in relation to an ongoing corruption probe, Bloomberg reported. Hong Kong’s Independent Commission Against Corruption (ICAC) also detained Rafael Hui, a former number two official in the government. Sun Hung Kai Properties said the brothers had been arrested in connection with an investigation of a Prevention of Bribery Ordinance violation, but that the detentions will not affect regular business operations. This marks one of the highest-profile cases in the ICAC’s 38 years. Sun Hung Kai stock plunged as much as 15%, the most since January 1998, costing the company HK$45 billion (US$5.8 billion). The arrests come just days after the conclusion of Hong Kong’s election of a new chief executive – a campaign dominated by allegations of corruption surrounding candidate Henry Tang and outgoing chief executive Donald Tsang.