Markets regulator Securities and Exchange Board of India’s (Sebi’s) probe against the National Stock Exchange (NSE) in the preferential access controversy has reached a crucial stage. In June, the exchange will have to deal with the findings of an internal probe, a forensic audit by EY on its currency and cash segment and also reply to the show-cause notices issued by the Sebi last week. The internal committee set up by the NSE to pin responsibility for the lapses at its co-location facility is expected to submit its report soon. The report will be first submitted to the managing director