The key points from the document are: 1) Indian stock markets ended flat on the last day of the May futures and options series, with the Sensex closing down 0.21% and the Nifty down 0.19%. 2) Markets were in the red zone initially due to losses in banking and metal stocks, but regained some ground in the second half of the session. 3) Nifty futures closed above 8,300, an important support level, but a close below this level could shift sentiment more bearish. The 8,400 resistance level may also limit further upside.