Prices of coriander futures fell sharply over the last two months to hit five-year lows, despite strict curbs by the exchange, which has left not only the exchange, but also regulators in quandary about what could have led to the strong one-sided price movement. The contract has hit the 4% maximum lower circuit in at least six trading sessions over the last one month, despite NCDEX raising special margins by 20 percentage points. Concerned over allegations of excessive speculation in coriander futures contracts, SEBI is likely to hold a crucial meeting with NCDEX later in this week.