The derivative expiry for the May contract saw Nifty Futures roll over 76.27% of its positions to the June Futures contract. The June contract begins with an open interest of Rs 37,265 crore, while the total open interest in Nifty Futures (Futures and Options combined) is lighter by nearly Rs 12,000 crore.The benchmark NSE Nifty 50 closed at 24,833 on Thursday, with significant Call writing continuing to build between 24,800 and 25,000. For the June 5 weekly expiry, the total Call open interest acting as a resistance at the 25,000 level stands at Rs 34,426 crore, with maximum open interest of Rs 13,893 crore at the 25,000 Call, followed by Rs 10,076 crore at the 24,800 Call. Even though the Nifty settled above the 24,800 level, the index may face some pressure at the open due to the high open interest at the 24,800 Call strike.To provide perspective, the notional turnover traded in Call contracts between 24,800 and 25,000 for the June 6 expiry stood at Rs 1.3 lakh crore, with the maximum notional turnover of Rs 51,207 crore traded at the 24,800 Call.There is an ongoing tussle between Call and Put writers at the 24,800 level, with an open interest of Rs 9,054 crore at the 24,800 Put strike. A movement above 24,800 will require Call writers to unwind their positions and Put writers to defend this level.Any upward move in the Nifty 50 will require significant momentum and a shift in Call writing to higher strike prices. The index has struggled to breach the 25,000 mark in recent attempts, failing to sustain above it each time. Call writers have also built positions at the 25,500 level, with an open interest of Rs 10,315 crore.Ahead of expiry day, May 29, the Nifty faced stiff resistance every time it tried to climb past 25,000, with Call writers holding open interest positions exceeding Rs 1 lakh crore.Foreign investors are beginning the June contract on a cautious note. They rolled over 64.5% of their Nifty Futures positions from May to June. On May 29, the FPIs added Rs 2,385 crore in net short positions, bringing the total open interest in Nifty Futures to Rs 15,168.56 crore, which is lighter by Rs 8,300 crore.Their long positions have declined to 19.71% of total positions, and the long-short ratio has fallen to 0.25 at the start of the June contract. The FPIs are entering the June series with a higher proportion of short positions.F&O Expiry Day To Be Either Tuesday Or Thursday, No Changes Without Prior Nod: SEBI. Read more on Markets by NDTV Profit.