Indonesian stocks tumbled after MSCI raised concerns about their investability and warned of a potential downgrade to frontier-market status. The decision comes after months of consultation following MSCI’s proposal to tighten the definition of free float for Indonesian securities. Worries about price dislocation were evident last year when the JCI outperformed the MSCI Indonesia Index by a record margin. With so many JCI members thinly traded, passive fund managers say the benchmark has been effectively untrackable, pushing them instead toward the more stringent MSCI Index. “Foreign participation in the Indonesian market has reduced significantly because of concerns about macro and policy.