Nifty plunges 1.6% to five-month low; Sensex ends 1,248 points lower

BSE reported movement of 1.6%. Those are the figures as filed — what moves the price is how they sit against what the market already expected, not their absolute size.

This is an Input cost / crude event. India imports most of its crude, so input costs pass through to margins downstream and to the rupee. Producers and consumers of the same input move in opposite directions.

Because the driver here is macro rather than company-specific, the read-through is to index-level positioning rather than to any single name — correlations tend to rise when the whole market faces the same signal.