* Foreign investor outflow stands at $4.88 billion this year
SINGAPORE, Oct 19 (Reuters) - Indonesian markets face a tense start on Monday after a warning from MSCI over possible expulsion from some of its indexes next year rattled already fragile investor sentiment and sparked a furious selloff in the world's worst-performing stock market.
Jakarta stocks sank 11.6% on Friday, the benchmark's biggest one-day drop in nearly three decades, taking year-to-date losses to 40%, after MSCI said it was considering shifting Indonesia to "standalone" status from its current "emerging markets" mantle.
The index provider had threatened a downgrade to "frontier" status in January because of opacity in ownership and trading behaviour but said on Friday the lack of progress in remedying those concerns meant even a downgrade to that status would not reflect the severity of the issues.
A shift to standalone status would risk cutting Southeast Asia's biggest economy off from international capital, relegate it to an investment backwater and club it with a group of standalone markets that includes Lebanon and Zimbabwe.