JAKARTA, Oct. 19 -- The Indonesia Stock Exchange has decided to stop counting some of the country's most tightly held companies in its own headline index, a concession announced on Monday, the day the benchmark sank to its lowest level in six years.

Nikkei Asia reported that every stock flagged for high shareholding concentration, known as HSC, will be excluded from the Jakarta Composite Index. The paper counts 80 such stocks, together carrying 18% of the index's weighting. The decision followed an online conference on Monday afternoon with MSCI, the index provider now weighing whether to demote Indonesia.

The stakes are written into MSCI's own release. On October 15 it called Indonesia's continued classification as an emerging market "...