To curb excessive volatility in mid and small-cap counters, BSE has introduced a new surveillance measure for certain stocks having a market capitalisation of less than Rs 1,000 crore. The new measure, add-on price band framework, will apply to companies with a market-capitalisation of less than Rs 1,000 crore and on securities in groups -- X, XT, Z, ZP, ZY, and Y, BSE said in a circular on Wednesday.