Mumbai, Oct. 29 -- Many analysts were left perplexed by foreign portfolio investors' (FPI) huge net purchase figure of Rs.10,339.8 crore in the equity cash market on Tuesday, despite there being no rebalancing of benchmark indices like the Nifty nor many significant block deals.

The last Tuesday of every month sees Nifty futures and options (F&Os) and stock F&Os being rolled over or allowed to expire.

Around 122,914 stock futures contracts were closed out by FPIs on the expiry day, leaving them with 1.27 million stock futures contracts versus 1.393 million a day earlier, as shown by data from NSE.

This meant these futures were converted into delivery, resulting in the inflated buying figure on the stock exchange.

There were no large b...