Hong Kong CNN — China’s banks and insurers have become the latest focus of a sweeping anti-corruption crackdown that is ensnaring top officials and risks rattling the already fragile nerves of investors and entrepreneurs. The Communist Party’s top anti-graft agency, the Central Commission for Discipline Inspection (CCDI), has investigated more than a dozen senior executives at the country’s most important financial institutions so far this year, according to a CNN analysis of statements posted on the CCDI’s website. Three big names at the very top of China’s financial system have been probed or charged, according to the CCDI, including Li…